Concrete Resources

Aggregate Quantity Guide

How to estimate aggregate quantity for concrete, sub-base, backfill, drainage, and landscaping — covering bulk density, volume-to-weight conversion, wastage, compaction, brass and tonne units, and IS 383:2016 standards.

Last updated: June 18, 2026

Aggregate quantity estimation sounds straightforward — measure the area, multiply by depth, get the volume. But the gap between a rough volume and an accurate order quantity involves bulk density, compaction, wastage, moisture, and unit conversion decisions that are wrong on most construction sites. Under-order and the project stalls. Over-order and the excess sits on site, paid for and unused.

This guide explains the complete estimation method for any aggregate application — concrete, sub-base, backfill, drainage, and landscaping — with worked examples, reference tables, and the unit conversion logic that connects cubic metres to tonnes, brass, cubic yards, and truck loads.

The Six-Step Estimation Method

Every aggregate quantity calculation follows the same six-step sequence regardless of material type or application. The steps are listed below; each is explained in detail in the sections that follow.

Step	What it does	Formula	Notes
Step 1	Measure dimensions	Length (m) × Width (m) × Depth (m) = Volume (m³)	Use metres for all dimensions. Convert mm depth: divide by 1,000
Step 2	Apply compaction factor	Loose volume = Volume × (1 + compaction %)	Only for compacted layers (sub-base, backfill). Skip for concrete batching
Step 3	Convert to weight	Weight (kg) = Loose volume × Bulk density (kg/m³)	Use material-specific density, not a generic value
Step 4	Apply moisture factor	Adjusted weight = Dry weight × moisture factor	Dry = 1.00, Damp = 1.10, Wet = 1.22
Step 5	Add wastage	Order quantity = Adjusted weight × (1 + wastage %)	Minimum 5% for any manually handled material
Step 6	Convert to delivery units	Tonnes = kg ÷ 1,000 \| Brass = m³ ÷ 2.832 \| Loads = kg ÷ truck capacity	Match the unit your supplier quotes

The Aggregate Weight Calculator on this site automates all six steps simultaneously. Enter your dimensions, select your material, and set your wastage and compaction — the calculator handles the rest and outputs the result in tonnes, brass, bags, and truck loads.

Want to skip the manual steps and get an instant result?

Use our Aggregate Weight Calculator →

Bulk Density — The Key Conversion Factor

Bulk density is the mass of aggregate per unit volume of the container — including the air gaps between particles. It is the number that converts your volume calculation into the weight your supplier needs for the order. It is not the same as specific gravity (particle density), which excludes inter-particle voids and is used only in concrete mix design.

Loose Bulk Density

Aggregate poured freely into container
Represents stockpile and delivery condition
Used for ordering and weight estimation
IS 2386 (Part III): pour from ≤5cm height, strike off level

Rodded Bulk Density

Aggregate filled in 3 layers, 25 strokes each
Represents compacted or concrete batching condition
Always higher than loose density
IS 2386 (Part III): 16mm tamping rod, uniform strokes

Aggregate Type	IS 383 Classification	Loose Bulk Density (kg/m³)	Typical Use
River Sand (Zone II)	Fine aggregate	1,550–1,650	Concrete, mortar, plastering
M Sand / Manufactured Sand	Fine aggregate	1,700–1,800	Concrete, masonry — IS 383:2016 Zone II
Stone Dust (Zone IV)	Fine aggregate	1,600–1,700	Plastering, masonry mortar
10mm Crushed Granite	Coarse aggregate	1,580–1,650	Concrete, pathways
20mm Crushed Granite	Coarse aggregate	1,550–1,650	RCC concrete — most common size
40mm Crushed Granite	Coarse aggregate	1,500–1,600	Mass concrete, PCC, select footings
Crushed Limestone (20mm)	Coarse aggregate	1,450–1,550	Concrete, road base
River Gravel / Pea Gravel	Coarse aggregate	1,450–1,520	Drainage, decorative, paths
GSB (Granular Sub-Base)	Road aggregate	1,650–1,750	Road sub-base, IRC SP:49
WMM (Wet Mix Macadam)	Road aggregate	1,750–1,900	Road base course
MOT Type 1 / Crusher Run	Sub-base	1,850–1,950	Driveway base, road sub-base
Recycled Concrete Aggregate	Coarse aggregate	1,100–1,400	Non-structural fill, limited RCC use

All values are dry condition. Wet aggregate weighs 10–20% more for the same volume. Values vary by quarry source, grading, and particle shape.

If your supplier provides a tested bulk density for their specific aggregate, use that value instead of the reference table. A 5% difference in bulk density produces a 5% difference in order quantity — on a 40-tonne order, that is 2 tonnes.

Want to measure your aggregate's bulk density from a field test?

Use our Aggregate Density Calculator →

Wastage Factors by Application

Wastage accounts for aggregate lost during delivery unloading, site handling, spreading, wind (for fine sand), and material left on vehicle beds. It is applied to the adjusted weight after moisture correction, because the waste includes both dry aggregate and any absorbed moisture it carries.

Application	Recommended Wastage	Notes
Concrete batching (plant)	3–5%	Controlled process, weigh batching
Concrete mixing (site, manual)	5–8%	Shovelling and loading loss
RCC slab or beam pour	5–7%	Formwork-contained, moderate loss
Backfill / plinth filling	5–10%	Irregular excavation edges, spreading loss
Road sub-base — GSB (machine-laid)	5–7%	Mechanical spreading, lower loss
Road sub-base — WMM (machine-laid)	5–7%	Machine-laid, controlled
Drainage trench (hand-filled)	8–12%	Irregular trench geometry
Decorative gravel / garden	8–12%	Edge loss, spreading over-run
Driveway sub-base (hand-laid)	8–10%	Edge trimming, uneven ground
Concrete block or paver bedding	5–8%	Edge waste and over-spreading

Never use 0% wastage in a residential estimate. Even for machine-laid road base, residual material on the truck bed, edge overshoot, and minor grading variation account for at least 3%. For any hand-poured or hand-spread application, 5% is the absolute minimum.

Compaction Factors

When aggregate is placed loose and then compacted, the finished layer is thinner (denser) than the loose material. To achieve the required finished thickness, you must order extra loose material to account for this reduction. The compaction factor expresses this as a percentage of the finished volume.

Loose volume needed = Finished volume × (1 + Compaction factor)

Example: 12 m³ finished GSB layer with 12% compaction:

12.00 × 1.12 = 13.44 m³ loose to order

Material	Compaction Factor	Notes
River sand (backfill)	8–12%	Hand or plate compaction
GSB (Granular Sub-Base)	12–15%	Mechanical compaction per IRC SP:49
WMM (Wet Mix Macadam)	10–13%	Roller compaction
Crushed stone sub-base	12–18%	Plate compactor or roller
Pea gravel / drainage gravel	0%	Not compacted — must remain open-graded
Decorative gravel	5–8%	Light foot traffic settling
Driveway sub-base (MOT Type 1)	15–25%	Plate compactor, multiple passes
Soil-aggregate fill	20–30%	Depends on equipment and soil type

Do not apply compaction factor to aggregate for concrete batching. Concrete aggregate is measured and batched by weight before mixing — there is no compaction of loose aggregate. Applying a compaction factor to concrete aggregate over-estimates your order by 10–20%.

Worked Examples

Four complete examples covering different materials, applications, and countries — showing every step of the six-step method with actual numbers substituted.

Example 1 — GSB Sub-Base for a Residential Ground Floor

India (Hyderabad)

A contractor is preparing a 150mm thick GSB layer under PCC for a 10m × 8m ground floor. The GSB will be machine-compacted.

Step	Formula / Substitution	Result
Finished (compacted) volume	10 × 8 × 0.150	12.00 m³
Apply compaction factor (12%)	12.00 × 1.12	13.44 m³ loose
GSB bulk density	1,700 kg/m³	—
Dry weight	13.44 × 1,700	22,848 kg
Wastage (6%)	22,848 × 1.06	24,219 kg = 24.22 tonnes
In brass	13.44 ÷ 2.832	4.75 brass (order 5 brass)
Truck loads (10T)	24,219 ÷ 10,000	2.4 loads → order 3 loads

The compaction factor is critical here. Without it, the estimate would be 22.5% short — 2 truck loads instead of 3.

Example 2 — Coarse Aggregate for a Residential Slab (M20 Concrete)

India (Pune)

A homeowner is casting an 8m × 6m × 0.125m RCC slab using M20 nominal mix (1:1.5:3) with 20mm crushed granite, site-mixed.

Step	Formula / Substitution	Result
Slab concrete volume	8 × 6 × 0.125	6.00 m³
Coarse aggregate per m³ (M20 nominal)	0.84 m³ bulk volume	—
Total coarse aggregate volume	6.00 × 0.84	5.04 m³ bulk
Bulk density (20mm granite)	1,600 kg/m³	—
Dry weight	5.04 × 1,600	8,064 kg
Wastage (7% for site mixing)	8,064 × 1.07	8,628 kg = 8.63 tonnes
In brass	5.04 ÷ 2.832	1.78 brass → order 2 brass

Fine aggregate (sand) for this slab is a separate calculation: 6.00 × 0.44 × 1,600 × 1.07 = 4,513 kg ≈ 4.51 tonnes. Use the Sand Weight Calculator for sand estimation.

Example 3 — Pea Gravel for a Drainage Trench

UK (Birmingham)

A drainage contractor is filling a 25m × 0.5m × 0.6m French drain trench with single-size drainage gravel. No compaction — gravel must stay open-graded for drainage.

Step	Formula / Substitution	Result
Trench volume	25 × 0.5 × 0.6	7.50 m³
Compaction factor	0% (drainage gravel)	7.50 m³
Pea gravel bulk density	1,500 kg/m³	—
Dry weight	7.50 × 1,500	11,250 kg
Wastage (5%)	11,250 × 1.05	11,813 kg = 11.81 tonnes
In cubic yards	7.50 ÷ 0.765	9.80 yd³
Truck loads (10T)	11,813 ÷ 10,000	1.2 loads → order 2 loads

Do not compact single-size drainage gravel. Compaction fills the inter-particle voids and destroys the drainage performance.

Example 4 — Driveway Sub-Base (MOT Type 1)

UK (Manchester)

A homeowner is laying a 5m × 8m block paved driveway with 150mm compacted MOT Type 1 sub-base.

Step	Formula / Substitution	Result
Finished (compacted) area and depth	5 × 8 × 0.150	6.00 m³
Compaction factor (20%)	6.00 × 1.20	7.20 m³ loose
MOT Type 1 bulk density	1,900 kg/m³	—
Dry weight	7.20 × 1,900	13,680 kg
Wastage (8%)	13,680 × 1.08	14,774 kg = 14.77 tonnes
Bulk bags (850 kg each)	14,774 ÷ 850	17.4 → order 18 bulk bags
Truck loads (10T)	14,774 ÷ 10,000	1.5 loads → order 2 loads

MOT Type 1 weighs nearly 30% more per m³ than pea gravel. Users who apply the wrong density here under-order significantly.

Aggregate Quantity for Concrete (by Grade)

When estimating aggregate for concrete, both coarse and fine aggregate must be calculated separately. The proportions below are approximate values for nominal mix concrete per IS 10262. For design mix concrete, the actual proportions come from the mix design report.

Concrete Grade (Nominal Mix)	Aggregate Size	Coarse Aggregate per m³	Coarse Aggregate Weight	Fine Aggregate per m³	Fine Aggregate Weight
M15 (1:2:4)	20mm granite	~1.44 m³ (bulk)	~2,304 kg	~0.72 m³ (bulk)	~1,152 kg
M20 (1:1.5:3)	20mm granite	~0.84 m³ (bulk)	~1,344 kg	~0.44 m³ (bulk)	~704 kg
M25 (1:1:2)	20mm granite	~0.64 m³ (bulk)	~1,024 kg	~0.33 m³ (bulk)	~528 kg

Coarse aggregate bulk density assumed 1,600 kg/m³ (20mm crushed granite). Fine aggregate bulk density assumed 1,600 kg/m³ (river sand Zone II). Values are before wastage — add 5–8% for site mixing.

Need exact aggregate quantities for your concrete mix grade?

Use our Mix Design Calculator →

Estimating fine aggregate (sand) for concrete or plastering?

Use our Sand Weight Calculator →

Unit Conversion Reference

Aggregate is quoted in different units depending on country and supplier. The tables below give the conversion factors between volume units and between weight units. Converting between volume and weight requires the material bulk density and is handled by the Aggregate Unit Converter.

Volume Unit Conversions

From	m³	ft³	yd³	litres
1 m³	35.315 ft³	1.308 yd³	1,000 litres	0.353 brass
1 brass	2.832 m³	100 ft³	3.704 yd³	2,832 litres
1 yd³	0.765 m³	27 ft³	0.207 brass	765 litres
1 ft³	0.0283 m³	0.037 yd³	0.01 brass	28.32 litres

Weight Unit Conversions

From	kg	quintal	US ton	UK ton	lb
1 metric tonne	1,000 kg	10 quintals	1.102 US tons	0.984 UK tons	2,204.6 lb
1 quintal	100 kg	0.1 tonne	0.110 US tons	—	220.5 lb
1 US short ton	907.2 kg	9.072 quintals	0.907 tonne	0.893 UK tons	2,000 lb
1 UK long ton	1,016 kg	10.16 quintals	1.016 tonne	1.120 US tons	2,240 lb

1 Brass in kg and Tonnes — by Material

One brass = 100 cubic feet = 2.832 m³. The weight per brass depends on the material bulk density. This table is particularly useful for Indian projects where suppliers quote in brass.

Material	Bulk Density (kg/m³)	1 Brass in kg	1 Brass in tonnes	1 Brass in quintals
River Sand (Zone II)	1,600	4,531	4.53	45.31
M Sand (Concrete Grade)	1,750	4,955	4.96	49.56
20mm Crushed Granite	1,600	4,531	4.53	45.31
40mm Crushed Granite	1,550	4,389	4.39	43.89
GSB (Granular Sub-Base)	1,700	4,814	4.81	48.14
WMM (Wet Mix Macadam)	1,800	5,097	5.10	50.97
MOT Type 1 / Crusher Run	1,900	5,380	5.38	53.80
River Gravel / Pea Gravel	1,500	4,248	4.25	42.48

Need to convert between brass, cubic metres, tonnes, and truck loads?

Use our Aggregate Unit Converter →

Relevant Standards

Indian Standards

Standard	Coverage
IS 383:2016	Specification for Coarse and Fine Aggregates — defines aggregate classification, grading zones, quality requirements, and bulk density reference values for all construction aggregate types
IS 2386 (Part III) – 1963	Methods of Test for Aggregates: Specific Gravity, Density, Voids, Absorption and Bulking — the standard IS field test for measuring bulk density from container weights
IS 456:2000	Plain and Reinforced Concrete — governs aggregate size selection for structural concrete members; Clause 5.3.1 sets maximum size limits
IS 10262:2019	Concrete Mix Design Guidelines — used to determine exact coarse and fine aggregate proportions for design mix concrete at a given grade and workability
IRC SP:49	Guidelines for the Use of Dry Lean Concrete — also references GSB and WMM aggregate specifications and compaction standards for road sub-base

International References

Standard	Coverage
ASTM C29 / C29M	Standard Test Method for Bulk Density (Unit Weight) and Voids in Aggregate (USA) — the ASTM equivalent of the IS 2386 bulk density test using a calibrated container and standardised filling procedure
ASTM C33 / C33M	Standard Specification for Concrete Aggregates (USA) — defines grading and quality requirements for fine and coarse aggregate in concrete; uses size numbers rather than mm designations
BS EN 1097-3:1998	Tests for Mechanical and Physical Properties of Aggregates: Determination of Loose Bulk Density and Voids (UK/EU)
BS EN 12620:2002+A1:2008	Aggregates for Concrete (UK/EU) — specifies grading, quality, and classification for concrete aggregate including 10mm, 14mm, 20mm, and 40mm nominal sizes
AS 1141.4:1974	Methods for Sampling and Testing Aggregates: Bulk Density of Aggregates (Australia)

IS 383 and IS 2386 govern aggregate classification and testing in India. For projects outside India, refer to ASTM C33 (USA), BS EN 12620 (UK/EU), or AS 2758.1 (Australia). The estimation method — volume × bulk density × adjustment factors — is identical regardless of which standard governs the aggregate specification.

Common Mistakes

Using a Generic Density for All Aggregate Types

The single most common quantity estimation error. Many site engineers and homeowners use 1,600 kg/m³ for all aggregates, regardless of type. MOT Type 1 has a bulk density of 1,850–1,950 kg/m³ — nearly 20% heavier. GSB is 1,650–1,750 kg/m³. Pea gravel is 1,450–1,520 kg/m³. Using 1,600 kg/m³ for MOT Type 1 under-estimates the weight (and therefore the number of truck loads) by approximately 17%. Using 1,600 kg/m³ for pea gravel over-estimates the weight by approximately 7%. On a 30-tonne order of MOT Type 1, a 17% error means the project runs 5 tonnes short before completion. Always use the bulk density of the specific aggregate being ordered.

Forgetting the Compaction Factor for Sub-Base Layers

A 150mm compacted GSB layer requires ordering approximately 12–15% more loose material than the finished thickness suggests, because compaction reduces the layer volume. Site engineers who calculate from the finished drawing dimension and omit the compaction factor consistently run short of material before completing the layer. With a 10m × 8m area: correct order (with 12% compaction) is 24.2 tonnes; incorrect order (without compaction) is 21.6 tonnes — 2.6 tonnes short, approximately half a truck load. This mistake appears so regularly on residential sites because the compaction factor is invisible in the finished structure and nobody connects the material shortage to the estimation method.

Applying Compaction Factor to Concrete Aggregate

The opposite mistake — applying a compaction factor to aggregate destined for concrete batching. Aggregate for concrete is batched by weight before mixing. There is no compaction of loose aggregate on a concrete site. Applying a 10–15% compaction factor to concrete aggregate over-estimates the required quantity by the same margin and wastes money. Compaction factor applies only to aggregate that will be placed in a layer and subsequently compacted on site — sub-base, backfill, and fill layers. For concrete, the correct adjustment is the wastage factor (3–8% for batching losses), not a compaction factor.

Measuring Dimensions from Drawings Without Site Verification

Drawing dimensions are nominal — the structure as planned. On site, excavation widths are often wider than planned (equipment overcut), formwork adds thickness inside excavations, and finished surface levels may differ from design levels. The difference between drawing dimensions and as-built dimensions typically adds 5–15% to the true volume. For a backfill calculation, using drawing excavation dimensions without measuring the actual excavation almost always under-estimates the true volume. Measure on site after excavation, before ordering fill material.

Confusing Wet and Dry Weight When Ordering

Suppliers who quarry or dredge river aggregate deliver material that is damp to wet. When a supplier quotes per tonne, the wet weight includes both the aggregate and the absorbed and surface water. One tonne of wet river sand at 20% moisture content contains only 833 kg of dry aggregate — you are receiving less material per tonne than expected. For critical estimates, ask the supplier whether their quoted weight is on a wet or dry basis, or add 10–15% to your calculated order quantity when ordering wet material by weight to compensate for the moisture.

Estimation Method — Quick Reference

Application	Use Compaction?	Typical Wastage	Order Unit
Concrete batching (plant)	No	3–5%	Tonne / kg
Concrete mixing (site)	No	5–8%	Tonne / brass
GSB sub-base	Yes (12–15%)	5–7%	Tonne / brass / truck
WMM road base	Yes (10–13%)	5–7%	Tonne / truck
Backfill / plinth fill	Yes (8–12%)	5–10%	Tonne / brass / truck
Drainage trench gravel	No (0%)	5–8%	Tonne / m³
Driveway sub-base	Yes (15–20%)	8–10%	Tonne / bulk bag
Decorative gravel	No / light (5%)	8–12%	Bulk bag / tonne

Practical Site Checklist

Before placing an aggregate order:

Measure project dimensions on site, not from drawings alone — as-built dimensions often differ from plan dimensions.
Confirm aggregate type and size from the structural or design drawings before calculating or ordering.
Use the bulk density for your specific aggregate type — check with your supplier for a tested value or use IS 383:2016 reference values.
Apply compaction factor for all layers that will be compacted after placing — sub-base, backfill, and fill layers.
Do not apply compaction factor to aggregate for concrete batching — batching is by weight, not loose volume.
Add a minimum 5% wastage for any manually handled application; 8–10% for irregular areas and trench filling.
For drainage aggregate, set compaction factor to 0% — compacting single-size drainage gravel destroys its drainage performance.
Cross-check the supplier's unit (brass, tonne, cubic yard, bulk bag, truck load) against the converted value before placing the order.
Confirm wet or dry basis for supplier quotes — wet aggregate weighs 10–20% more per tonne than dry aggregate of the same type.
Store fine aggregate (sand) and coarse aggregate in separate, clearly marked stockpiles — mixing on site invalidates your quantity estimate.
For large projects (over 50 tonnes), request a grading certificate and bulk density test result from the supplier for each batch.
Record the calculation method and density value used, so the estimate can be verified or reproduced if quantities run short.

Final Verdict

Accurate aggregate estimation is a discipline of three correct decisions: the right bulk density for the specific material, the right compaction factor for the application, and the right wastage for the site conditions. Get all three right and your order quantity will match your project requirement within 2–5%. Miss any one of them and the error compounds.

Always use the bulk density of your specific aggregate type — not a generic 1,600 kg/m³ for all materials.
Apply compaction factor for all sub-base and backfill layers. Do not apply it to concrete aggregate.
Add at least 5% wastage for any manually handled aggregate; 8–12% for irregular areas and trench work.
Order by weight (tonne or quintal) rather than volume where possible — weight is not affected by packing state.
Convert supplier units to your calculated units before placing the order — check brass, cubic yards, and truck loads against your calculation.
Measure dimensions on site after excavation, not from drawings.

The Aggregate Weight Calculator on this site automates the entire six-step method. The Aggregate Unit Converter handles all unit cross-checks. Use both to verify your estimate before ordering.

Related calculators

Use these calculators when you need to turn this reference information into project quantities:

Aggregate Weight Calculator
Calculate aggregate quantity by weight from project dimensions — supports all aggregate types, wastage, compaction, and moisture.
Aggregate Density Calculator
Measure and verify bulk density, void content, and specific gravity of aggregate from IS 2386 field tests.
Aggregate Unit Converter
Convert between cubic metres, cubic yards, brass, kg, tonnes, quintals, US tons, bags, and truck loads.
Concrete Mix Design Calculator
Estimate coarse and fine aggregate quantities within a concrete mix for M20 and other grades.
Sand Weight Calculator
Calculate fine aggregate (sand) quantity separately — with bulking correction for damp sand.
Gravel Weight Calculator
Calculate gravel for driveways, drainage, paths, and sub-base applications in multiple shape modes.
Concrete Calculator
Estimate total concrete volume and material quantities for slabs, beams, columns, and footings.

Related resources

20mm vs 40mm Aggregate Guide
Understand the difference between 20mm and 40mm coarse aggregate for concrete. Covers IS 456 size rules, workability, strength, cost, typical applications, and when to use each size.
Concrete Mix Ratios Explained
Understand concrete mix ratios such as 1:2:4, 1:1.5:3, 1:3:6, 1:4:8, and 1:5:10, including grades, uses, water-cement ratio, curing, and cost.
Water-Cement Ratio Guide
Understand water-cement ratio in concrete, including formula, recommended W/C values, strength and durability effects, water per cement bag, exposure limits, and common site mistakes.
M20 Concrete Guide
Understand M20 concrete, including 20 MPa strength, 1:1.5:3 nominal mix ratio, common RCC applications, standards, curing, compaction, mistakes, and site checklist.
Concrete Curing Guide
Understand concrete curing methods, recommended curing periods for OPC, PPC, RCC members, slabs, columns, footings, hot weather concrete, and why curing affects strength and durability.
Concrete Cover Guide
Understand concrete cover thickness for RCC slabs, beams, columns, footings, water tanks, retaining walls, cover blocks, corrosion protection, fire resistance, and common site mistakes.
RCC Slab Thickness Guide
Understand common RCC slab thickness values for residential rooms, roof slabs, larger spans, commercial floors, and industrial applications, including span guidance, standards, concrete volume, cover, reinforcement, and curing.
RCC Footing Thickness & Size Guide
Understand RCC footing sizes and thicknesses for residential construction, including isolated, combined, strap, and raft footings, soil bearing capacity, footing depth, PCC, concrete cover, and common site mistakes.

FAQ

The standard method has three steps. First, calculate the volume of the area to be filled — length × width × depth, with all dimensions in metres. Second, multiply the volume by the bulk density of the aggregate type to get the dry weight in kg. Third, add a wastage factor (typically 5–10%) to get the final order quantity. For example, a 10m × 8m area with a 150mm GSB layer needs 10 × 8 × 0.15 = 12 m³. At 1,700 kg/m³ for GSB, that is 12 × 1,700 = 20,400 kg = 20.4 tonnes. With 5% wastage the order quantity is 21.4 tonnes. The bulk density of the specific aggregate type is the critical variable — using a generic value when your material has a significantly different density produces a proportionally wrong result.

Bulk density is the mass of aggregate — including the air voids between particles — per unit volume, expressed in kg/m³. It is the conversion factor between the volume you measure on site and the weight your supplier quotes. For 20mm crushed granite, typical bulk density is 1,550–1,650 kg/m³. For MOT Type 1 sub-base, it is 1,850–1,950 kg/m³. Using MOT Type 1 density for crushed granite (or vice versa) creates a 15–20% error in your order quantity — on a 50-tonne order, that is 7–10 tonnes wrong. Always use the density value for your specific aggregate type. Your supplier can provide a tested bulk density; if not available, use IS 383:2016 reference values for that aggregate classification.

Wastage depends on the application and how aggregate is handled on site. For concrete batching at a plant, 3–5% is realistic. For manual site mixing, 5–8%. For backfill and plinth filling, 5–10% because of irregular excavation edges. For road sub-base (GSB/WMM) laid by machine, 5–7%. For drainage trenches filled by hand, 8–12% because of irregular trench geometry. For plastering sand, 5–8%. Never use 0% wastage in an estimate unless aggregate is being delivered directly into a weigh hopper with no handling. For residential construction with manual handling, 5% is the minimum reasonable wastage allowance for any application.

A brass is an Indian construction unit equal to exactly 100 cubic feet of material, which is equivalent to 2.83168 cubic metres. It is widely used by aggregate and sand suppliers in South India, Maharashtra, and Gujarat to quote delivery quantities. To convert brass to tonnes, multiply by the bulk density: Tonnes = Brass × 2.83168 × Density (kg/m³) ÷ 1000. For river sand at 1,600 kg/m³: 1 brass = 2.83168 × 1,600 ÷ 1000 = 4.53 tonnes. For 20mm crushed granite at 1,600 kg/m³: 1 brass = 4.53 tonnes. For GSB at 1,700 kg/m³: 1 brass = 2.83168 × 1,700 ÷ 1000 = 4.81 tonnes. The weight per brass varies significantly by material type — never use a fixed brass-to-tonne conversion without specifying the material.

Compaction factor accounts for the volume reduction that occurs when loose aggregate is mechanically or manually compacted into a finished layer. A 150mm compacted GSB layer requires ordering approximately 168–173mm worth of loose material because compaction reduces the volume by 12–15%. The formula is: Loose volume needed = Finished (compacted) volume × (1 + Compaction factor). Typical compaction factors: GSB 12–15%, WMM 10–13%, backfill sand 8–12%, plate-compacted gravel sub-base 15–18%. Do not apply compaction factor to aggregate for concrete batching — aggregate for concrete is batched by weight and there is no compaction of loose aggregate before mixing. The most common estimation mistake is forgetting the compaction factor for sub-base layers, which causes truck loads to run short before the layer is complete.

For a nominal M20 mix (1:1.5:3 by volume), the coarse aggregate quantity is approximately 0.84 m³ bulk volume per 1 m³ of finished concrete, which equals approximately 1,340 kg using a bulk density of 1,600 kg/m³. Fine aggregate (sand) is approximately 0.44 m³ bulk volume per m³ of concrete, equalling approximately 704 kg. These figures are for nominal mix concrete. For design mix concrete per IS 10262:2019, the exact quantities depend on the aggregate grading, specific gravity, water content, and target strength — a laboratory mix design gives more accurate proportions. The Concrete Mix Design Calculator on this site computes these quantities for your specific inputs.

Multiply cubic metres by 1.30795 to get cubic yards. To go the other way, multiply cubic yards by 0.764555 to get cubic metres. These are pure volume conversions that do not depend on the material. To convert cubic yards to tonnes (which does depend on material), multiply: cubic yards × 0.764555 × bulk density (kg/m³) ÷ 1000. For 20mm crushed granite at 1,600 kg/m³: 5 cubic yards = 5 × 0.764555 × 1,600 ÷ 1000 = 6.12 tonnes. The Aggregate Unit Converter on this site handles all of these conversions simultaneously for any selected material.

IS 383:2016 defines fine aggregate as material passing a 4.75mm IS sieve — this includes natural river sand, manufactured sand (M sand), stone dust, and other fine materials. Coarse aggregate is material retained on the 4.75mm sieve and includes crushed granite, limestone, gravel, and other larger particles in sizes such as 10mm, 20mm, and 40mm. Both are used in concrete: fine aggregate fills the voids between coarse aggregate particles and, together with cement paste, binds the mix. For quantity estimation, fine and coarse aggregate must be calculated separately because their bulk densities and proportions in the mix differ. M sand (manufactured fine aggregate) has a higher bulk density than river sand and requires a separate calculation.

Weight-based estimation is more accurate than volume-based estimation for aggregate. Volume measurement is affected by the packing state of the aggregate — the same quantity of aggregate can occupy different volumes depending on how it is poured, whether it has been disturbed, and whether it is damp or dry. Fine sand is particularly prone to bulking — damp fine sand at 5–6% moisture can appear to occupy 25–35% more volume than the same dry sand. Coarse aggregate is less affected by bulking but still varies by 5–10% in volume depending on packing. Weight-based ordering (by tonne or quintal) is more reliable because weight does not change with packing state, only with moisture content. Always order aggregate by weight from your supplier, not by volume, unless the supplier measures and delivers by a calibrated volume unit (such as a standardised truck load).

Recycled concrete aggregate (RCA) is permitted under IS 383:2016 for limited applications — up to 25% replacement in plain concrete and 20% in reinforced concrete up to M25 grade. RCA has a lower and more variable bulk density than virgin aggregate, typically 1,100–1,400 kg/m³ compared to 1,550–1,650 kg/m³ for crushed granite. For quantity estimation, use the tested bulk density of the specific RCA batch, not a generic value, because it varies significantly by source. Higher water absorption of RCA (3–8% versus 0.5–2% for virgin granite) also means the mix design must account for pre-wetting or absorption correction. For structural RCC work, always confirm with the structural engineer before using RCA.