TryBuildCalcGravel Coverage at 50mm(Tonnes, Bags & Square Metres)
Calculate gravel coverage at 50mm.
🕒 Last updated: June 20, 2026
Inputs
ℹ️Auto-filled by material. Replace with supplier-tested density when available.
12.5 m²
135.0 ft²
At 50.0mm finished depth
0.63 m³
0.82 yd³
40 bags
Based on 25kg bags
Material: Decorative Gravel / Granite Chip
Density: 1,450 kg/m³
Wastage: 10% included
Coverage Visualizations
Coverage Area
Layer Depth Cross-Section
Practical Coverage at 50.0mm Depth
After 10% wastage
Approximate results for planning only. Verify with a professional.
Coverage at the common 50mm depth
Fifty millimetres is a common finished depth for paths, decorative areas, and driveway surface layers.
Material density still changes the area covered per tonne.
- Compare material types.
- Use zero wastage for table-style reference.
- Use 10% for practical ordering.
What Is a Gravel Coverage Calculator?
When you are planning a garden path, driveway, decorative border, or drainage project, gravel suppliers quote by the tonne or by the bag — but you are thinking in square metres. This calculator bridges that gap in both directions.
Enter your tonne or bag quantity and a target depth, and the calculator tells you exactly how much area you can cover. Or enter your area and depth, and it tells you how many tonnes or bags to order. Or enter your quantity and area, and it tells you what depth you will achieve.
Unlike generic coverage calculators that use a single fixed density for all gravel, this calculator uses the correct bulk density for each specific material. MOT Type 1 at 1,900 kg/m³ covers significantly less area per tonne than pea gravel at 1,480 kg/m³. Using the wrong density produces a coverage estimate that can be 20–30% wrong.
Who uses this calculator:
- Homeowners planning a gravel driveway, path, or garden feature
- Landscapers estimating decorative aggregate for planting beds
- DIY builders checking whether a bulk bag delivery will be enough
- Drainage contractors sizing aggregate backfill around pipes
- Anyone comparing how far a budget will stretch at different depths
Applicable standards
- IS 383:2016 — India
- BS EN 13242 — UK/Europe
- ASTM D448 — USA
- AS 2758.1 — Australia
How Is Gravel Coverage Calculated?
Gravel coverage is calculated from area, depth, density, and wastage allowance. The calculation first converts the required layer into a volume, then converts that volume into mass using the selected gravel density.
Step 1 — Convert depth to metres
Depth (m) = Depth (mm) ÷ 1,000
Depth must be in metres before calculating volume. For example, a 50 mm gravel layer is 50 ÷ 1,000 = 0.05 m deep.
Step 2 — Calculate gravel volume
Volume (m³) = Area (m²) × Depth (m)
If a path area is 20 m² and the gravel depth is 50 mm, the depth is 0.05 m. The volume is therefore 20 × 0.05 = 1.00 m³.
Step 3 — Convert volume into mass
Mass (kg) = Volume (m³) × Bulk Density (kg/m³)
Gravel is commonly sold by weight. If the volume is 1.00 m³ and the selected gravel density is 1,600 kg/m³, the base quantity is 1.00 × 1,600 = 1,600 kg, or 1.60 tonnes.
Step 4 — Add wastage when calculating order quantity
Order Mass = Base Mass × (1 + Wastage ÷ 100)
Wastage covers spreading loss, edge migration, settlement, uneven ground, and handling loss. If the base quantity is 1,600 kg and wastage is 10%, order mass = 1,600 × 1.10 = 1,760 kg.
Step 5 — Reduce coverage when quantity is fixed
Usable Coverage Area = Supplied Mass ÷ [Density × Depth × (1 + Wastage ÷ 100)]
When you already have a fixed quantity, wastage reduces the practical area it can cover. For example, 1,000 kg of gravel at 1,500 kg/m³ and 50 mm depth covers 13.33 m² before wastage, but only about 12.12 m² with a 10% allowance.
Step 6 — Calculate achievable depth from quantity and area
Depth (m) = Supplied Mass ÷ [Area × Density]
This mode is useful when you already have a bulk bag and want to know how thick the layer will be. After calculating depth in metres, multiply by 1,000 to convert the result back to millimetres.
Worked Gravel Coverage Examples
The examples below show how to enter real site measurements into the gravel coverage formula. Each example lists the calculator inputs first, then applies the same formula steps used by the calculator: convert depth, calculate volume, convert volume to mass using bulk density, and apply wastage or compaction allowance where required.
Formula reminder: use FIND QUANTITY when area and depth are known, FIND AREA when quantity and depth are known, and FIND DEPTH when quantity and area are known. The core formulas are: Volume = Area × Depth, Mass = Volume × Density, and Order Mass = Base Mass × (1 + Allowance ÷ 100).
Example 1 — Calculate Gravel Required for a Garden Path
Calculator mode: FIND QUANTITY
A homeowner wants to build a decorative garden path that is 12 m long and 0.8 m wide. The selected gravel is golden flint with an assumed loose bulk density of 1,500 kg/m³. The gravel layer will be 40 mm deep, and a 10% wastage allowance is added for spreading loss, edge migration, and settlement.
Input details
These are the values the user would enter or select in the calculator before reading the result.
| Input | Value | Why it matters |
|---|---|---|
| Calculator mode | FIND QUANTITY | Use this mode when the area and depth are known, and the calculator must find how much gravel to order. |
| Material | Golden flint / decorative gravel | Use the matching gravel type or manually enter density. |
| Bulk density | 1,500 kg/m³ | This converts gravel volume into weight. |
| Length | 12 m | Used to calculate path area. |
| Width | 0.8 m | Used to calculate path area. |
| Depth | 40 mm | Decorative path layer thickness. |
| Wastage | 10% | Allows for spreading loss and later settlement. |
| Bag size | 850 kg bulk bag | Used to convert final quantity into bags. |
Step-by-step calculation
The table below shows how the input values are placed into the formula and converted into the final result.
| Step | Formula / Substitution | Result |
|---|---|---|
| Calculate area | Area = Length × Width | 12 × 0.8 = 9.60 m² |
| Convert depth to metres | Depth (m) = Depth (mm) ÷ 1,000 | 40 ÷ 1,000 = 0.04 m |
| Calculate gravel volume | Volume = Area × Depth | 9.60 × 0.04 = 0.384 m³ |
| Convert volume to mass | Mass = Volume × Density | 0.384 × 1,500 = 576 kg |
| Add wastage | Order Mass = Base Mass × 1.10 | 576 × 1.10 = 633.6 kg |
| Convert to tonnes | Tonnes = kg ÷ 1,000 | 633.6 ÷ 1,000 = 0.63 tonnes |
| Convert to bulk bags | Bags = Order Mass ÷ Bag Size | 633.6 ÷ 850 = 0.75 bag → order 1 bulk bag |
Result
The path requires about 634 kg, or 0.63 tonnes, of decorative gravel. Since gravel is commonly delivered in 850 kg bulk bags, one bulk bag is sufficient, with spare material for topping up after settlement.
Practical note
For paths, edging is important. Without edging, gravel spreads into the lawn or soil border, reducing the effective depth and increasing future top-up quantity.
Example 2 — Calculate Driveway Surface Gravel Quantity
Calculator mode: FIND QUANTITY
A driveway is 5 m wide and 8 m long. The owner wants a 50 mm loose surface layer using 20 mm granite gravel. The assumed loose bulk density is 1,600 kg/m³. A 10% allowance is added for spreading, settlement, and small surface irregularities.
Input details
These are the values the user would enter or select in the calculator before reading the result.
| Input | Value | Why it matters |
|---|---|---|
| Calculator mode | FIND QUANTITY | Use this mode when the driveway area and required surface depth are known. |
| Material | 20 mm granite gravel | Dense decorative or driveway surface gravel. |
| Bulk density | 1,600 kg/m³ | Granite is denser than slate or pea gravel. |
| Length | 8 m | Driveway length. |
| Width | 5 m | Driveway width. |
| Depth | 50 mm | Loose driveway surface gravel layer. |
| Wastage | 10% | Allows for spreading loss, uneven level, and settlement. |
| Bag size | 1,000 kg bulk bag / tonne bag | Useful for ordering. |
Step-by-step calculation
The table below shows how the input values are placed into the formula and converted into the final result.
| Step | Formula / Substitution | Result |
|---|---|---|
| Calculate area | Area = Length × Width | 8 × 5 = 40.00 m² |
| Convert depth to metres | Depth (m) = Depth (mm) ÷ 1,000 | 50 ÷ 1,000 = 0.05 m |
| Calculate volume | Volume = Area × Depth | 40.00 × 0.05 = 2.00 m³ |
| Convert volume to mass | Mass = Volume × Density | 2.00 × 1,600 = 3,200 kg |
| Add wastage | Order Mass = Base Mass × 1.10 | 3,200 × 1.10 = 3,520 kg |
| Convert to tonnes | Tonnes = kg ÷ 1,000 | 3,520 ÷ 1,000 = 3.52 tonnes |
| Convert to 1-tonne bags | Bags = Order Mass ÷ 1,000 | 3,520 ÷ 1,000 = 3.52 bags → order 4 tonne bags if bags are the only option |
Result
The driveway surface layer requires about 3.52 tonnes of 20 mm granite gravel. If the supplier delivers only full 1-tonne bags, round up to 4 bags. If loose bulk delivery is available, order close to 3.5 tonnes plus supplier rounding.
Practical note
This example calculates only the loose surface gravel layer. A driveway normally also needs a compacted sub-base such as crusher run, MOT Type 1, or GSB. Calculate the sub-base separately because it uses different density, depth, and compaction assumptions.
Example 3 — Check How Much Area One Bulk Bag Covers
Calculator mode: FIND AREA
A user already has one 850 kg bulk bag of river gravel and wants to know how much area it will cover at 50 mm depth. The assumed loose bulk density is 1,450 kg/m³. A 10% practical allowance is included to avoid spreading the gravel too thin.
Input details
These are the values the user would enter or select in the calculator before reading the result.
| Input | Value | Why it matters |
|---|---|---|
| Calculator mode | FIND AREA | Use this mode when the available gravel quantity and required depth are known, and the calculator must find coverage area. |
| Material | River gravel | Rounded natural gravel used for gardens and decorative areas. |
| Bulk density | 1,450 kg/m³ | Used to convert the 850 kg bag into volume. |
| Quantity | 850 kg | One standard bulk bag. |
| Depth | 50 mm | Target finished gravel thickness. |
| Wastage / allowance | 10% | Reduces practical coverage area. |
Step-by-step calculation
The table below shows how the input values are placed into the formula and converted into the final result.
| Step | Formula / Substitution | Result |
|---|---|---|
| Convert quantity to kg | Supplied Mass = 850 kg | 850 kg |
| Calculate available volume | Volume = Mass ÷ Density | 850 ÷ 1,450 = 0.586 m³ |
| Convert depth to metres | Depth (m) = Depth (mm) ÷ 1,000 | 50 ÷ 1,000 = 0.05 m |
| Coverage before wastage | Coverage = Volume ÷ Depth | 0.586 ÷ 0.05 = 11.72 m² |
| Apply wastage allowance | Usable Coverage = Base Coverage ÷ 1.10 | 11.72 ÷ 1.10 = 10.65 m² |
Result
One 850 kg bulk bag of river gravel covers about 11.7 m² at 50 mm depth before wastage. With a 10% practical allowance, use about 10.6 m² as the safer coverage estimate.
Practical note
This is why many suppliers say one bulk bag covers roughly 10–12 m² at 50 mm depth. The exact value depends on gravel density, moisture, grading, and how evenly the material is spread.
Example 4 — Check Achievable Depth from a Fixed Quantity
Calculator mode: FIND DEPTH
A user has one 850 kg bulk bag of gravel and wants to spread it over a 10 ft × 12 ft patio border. Instead of asking how much area the bag covers, the question is: what depth will this bag achieve over the known area?
Input details
These are the values the user would enter or select in the calculator before reading the result.
| Input | Value | Why it matters |
|---|---|---|
| Calculator mode | FIND DEPTH | Use this mode when the gravel quantity and area are known, and the calculator must calculate achievable depth. |
| Material | River gravel | Assumed loose density of 1,450 kg/m³. |
| Bulk density | 1,450 kg/m³ | Used to convert mass into volume. |
| Quantity | 850 kg | One bulk bag. |
| Area | 10 ft × 12 ft | Area must be converted to m² before using the formula. |
| Wastage / allowance | 10% | Used to estimate practical depth after settlement and spreading loss. |
Step-by-step calculation
The table below shows how the input values are placed into the formula and converted into the final result.
| Step | Formula / Substitution | Result |
|---|---|---|
| Calculate area in ft² | Area = Length × Width | 10 × 12 = 120 ft² |
| Convert area to m² | Area (m²) = Area (ft²) × 0.092903 | 120 × 0.092903 = 11.15 m² |
| Calculate available volume | Volume = Mass ÷ Density | 850 ÷ 1,450 = 0.586 m³ |
| Calculate depth in metres | Depth = Volume ÷ Area | 0.586 ÷ 11.15 = 0.0526 m |
| Convert depth to mm | Depth (mm) = Depth (m) × 1,000 | 0.0526 × 1,000 = 52.6 mm |
| Apply 10% allowance | Practical Depth = Base Depth ÷ 1.10 | 52.6 ÷ 1.10 = 47.8 mm |
Result
One 850 kg bulk bag spread over a 10 ft × 12 ft area gives about 53 mm depth before wastage, or about 48 mm practical depth with a 10% allowance.
Practical note
This example is useful when the user already has material on site and wants to know whether it is enough for the intended area.
Example 5 — Estimate MOT Type 1 for a Driveway Sub-Base
Calculator mode: FIND QUANTITY
A small driveway sub-base is 4 m wide and 6 m long. The required compacted thickness is 150 mm. MOT Type 1 / crusher run is assumed at 1,900 kg/m³ loose bulk density. A 15% allowance is used to account for compaction and small level variations.
Input details
These are the values the user would enter or select in the calculator before reading the result.
| Input | Value | Why it matters |
|---|---|---|
| Calculator mode | FIND QUANTITY | Use this mode when the sub-base area and depth are known, and the calculator must find the order quantity. |
| Material | MOT Type 1 / crusher run | Dense graded sub-base material with fines. |
| Bulk density | 1,900 kg/m³ loose | Loose density used for ordering estimate. |
| Length | 6 m | Driveway length. |
| Width | 4 m | Driveway width. |
| Depth | 150 mm | Target compacted sub-base thickness. |
| Compaction / allowance | 15% | Allows for loose-to-compacted reduction and surface variation. |
Step-by-step calculation
The table below shows how the input values are placed into the formula and converted into the final result.
| Step | Formula / Substitution | Result |
|---|---|---|
| Calculate area | Area = Length × Width | 6 × 4 = 24.00 m² |
| Convert depth to metres | Depth (m) = Depth (mm) ÷ 1,000 | 150 ÷ 1,000 = 0.15 m |
| Calculate compacted layer volume | Volume = Area × Depth | 24.00 × 0.15 = 3.60 m³ |
| Convert volume to mass | Base Mass = Volume × Density | 3.60 × 1,900 = 6,840 kg |
| Add compaction allowance | Order Mass = Base Mass × 1.15 | 6,840 × 1.15 = 7,866 kg |
| Convert to tonnes | Tonnes = kg ÷ 1,000 | 7,866 ÷ 1,000 = 7.87 tonnes |
Result
The driveway sub-base requires approximately 7.9 tonnes of MOT Type 1 / crusher run, assuming 150 mm compacted depth and a 15% allowance.
Practical note
For sub-base work, supplier density, compaction method, layer thickness, and project specification matter. Do not calculate compacted roadbase exactly the same way as loose decorative gravel.
Gravel Coverage Reference Tables
Coverage per Tonne at Common Depths by Material
| Material | Density (kg/m³) | 25mm | 40mm | 50mm | 75mm | 100mm |
|---|---|---|---|---|---|---|
| Slate Chip | 1,420 | 28.2m² | 17.6m² | 14.1m² | 9.4m² | 7.0m² |
| Pea Gravel / Pea Shingle | 1,480 | 27.0m² | 16.9m² | 13.5m² | 9.0m² | 6.8m² |
| River Gravel (20mm) | 1,500 | 26.7m² | 16.7m² | 13.3m² | 8.9m² | 6.7m² |
| Decorative Granite Chip | 1,450 | 27.6m² | 17.2m² | 13.8m² | 9.2m² | 6.9m² |
| Crushed Granite (10mm) | 1,600 | 25.0m² | 15.6m² | 12.5m² | 8.3m² | 6.3m² |
| Crushed Granite (20mm) | 1,600 | 25.0m² | 15.6m² | 12.5m² | 8.3m² | 6.3m² |
| Crushed Limestone (20mm) | 1,490 | 26.8m² | 16.8m² | 13.4m² | 8.9m² | 6.7m² |
| GSB (Granular Sub-Base) | 1,700 | 23.5m² | 14.7m² | 11.8m² | 7.8m² | 5.9m² |
| MOT Type 1 / Crusher Run | 1,900 | 21.1m² | 13.2m² | 10.5m² | 7.0m² | 5.3m² |
| Recycled Concrete Gravel | 1,350 | 29.6m² | 18.5m² | 14.8m² | 9.9m² | 7.4m² |
Coverage area per 1 tonne. Wastage is not included.
Coverage per Bulk Bag (850kg)
| Material | 25mm | 40mm | 50mm | 75mm |
|---|---|---|---|---|
| Pea Gravel (1,500kg/m³) | 22.7m² | 14.2m² | 11.3m² | 7.6m² |
| Decorative Granite Chip (1,450kg/m³) | 23.4m² | 14.7m² | 11.7m² | 7.8m² |
| 20mm Crushed Granite (1,600kg/m³) | 21.3m² | 13.3m² | 10.6m² | 7.1m² |
| MOT Type 1 (1,900kg/m³) | 17.9m² | 11.2m² | 8.9m² | 6.0m² |
Typical Depth Recommendations by Application
| Application | Minimum | Recommended | Notes |
|---|---|---|---|
| Decorative border / pots | 25mm | 30–40mm | Aesthetic only |
| Garden path (foot traffic) | 40mm | 50mm | Loose surface; use edging |
| Patio / seating area | 40mm | 50mm | Angular gravel for stability |
| Driveway (light vehicles) | 50mm | 50–75mm | Compactable gravel only |
| Driveway sub-base | 100mm | 150mm | MOT Type 1 / crusher run |
| Pipe bedding | 75mm | 100mm | Single-size only; no fines |
| French drain | 150mm | 200–300mm | Single-size; no compaction |
| Weed suppression | 40mm | 50mm | Over geotextile membrane |
| Flat roof ballast | 50mm | 50–75mm | Check structural capacity |
Coverage per 25kg Bag
| Material | 20mm | 30mm | 40mm | 50mm |
|---|---|---|---|---|
| Pea Gravel (1,500kg/m³) | 0.83m² | 0.56m² | 0.42m² | 0.33m² |
| 20mm Granite (1,600kg/m³) | 0.78m² | 0.52m² | 0.39m² | 0.31m² |
| Decorative Chip (1,450kg/m³) | 0.86m² | 0.57m² | 0.43m² | 0.34m² |
Essential Checklist+−
Complete these critical checks before approving the work or proceeding to the next construction stage.
✓Area Measurement+-
- Dimensions were measured on site — not estimated from memory or taken from drawings.
- Irregular or L-shaped areas were split into rectangles and each section measured separately.
✓Depth and Application+-
- Depth is appropriate for the application — decorative paths 30–50mm, driveways 50–75mm, drainage 100–150mm.
- The depth entered is the finished (compacted) depth, not the loose depth — compaction will be applied separately.
- Depth is entered in the correct unit — do not mix mm and cm.
- For roof ballast, structural engineer approval for the dead load has been obtained before ordering.
✓Gravel Type and Size+-
- Gravel type is confirmed — decorative (rounded), drainage (single-size angular), driveway (self-binding or crusher run), or sub-base.
- Drainage applications use single-size open-graded gravel — no fines, no crusher run, no self-binding gravel.
- Self-binding gravel or crusher run is specified for driveways — loose decorative gravel displaces under vehicles.
- Bulk density used in the calculator matches the gravel type — pea gravel ~1,500 kg/m³, MOT Type 1 ~1,900 kg/m³.
✓Compaction+-
- Compaction factor is applied for all base layers, driveway sub-base, and self-binding gravel.
- Compaction is set to 0% for single-size drainage gravel — compacting drainage gravel destroys its drainage performance.
- Compaction is set to 0% for loose decorative gravel and garden paths where no compaction is applied.
✓Wastage+-
- Wastage of at least 5% is added for all manually spread gravel.
- The quantity including wastage — not the net coverage quantity — is used for ordering.
✓Before Purchase+-
- The coverage area result was cross-checked against the measured site area.
Full QC Checklist+−
Use this checklist before relying on the gravel coverage estimate.
✓Area Measurement+-
- Dimensions were measured on site — not estimated from memory or taken from drawings.
- Irregular or L-shaped areas were split into rectangles and each section measured separately.
- For circular driveways or paths, the radius — not the diameter — was entered.
- Fixed features (manholes, planted areas, built-in borders) were deducted before entering area.
✓Depth and Application+-
- Depth is appropriate for the application — decorative paths 30–50mm, driveways 50–75mm, drainage 100–150mm.
- The depth entered is the finished (compacted) depth, not the loose depth — compaction will be applied separately.
- Depth is entered in the correct unit — do not mix mm and cm.
- For roof ballast, structural engineer approval for the dead load has been obtained before ordering.
- Driveway gravel depth accounts for vehicle loads — light vehicles need minimum 50mm, heavy vehicles 75mm.
✓Gravel Type and Size+-
- Gravel type is confirmed — decorative (rounded), drainage (single-size angular), driveway (self-binding or crusher run), or sub-base.
- Drainage applications use single-size open-graded gravel — no fines, no crusher run, no self-binding gravel.
- Self-binding gravel or crusher run is specified for driveways — loose decorative gravel displaces under vehicles.
- Gravel size is appropriate — 10mm or 20mm for paths, 20mm for drainage, 20–40mm for driveways.
- Gravel name matches the supplier's local terminology (MOT Type 1, pea gravel, hoggin, crusher run).
- Bulk density used in the calculator matches the gravel type — pea gravel ~1,500 kg/m³, MOT Type 1 ~1,900 kg/m³.
✓Compaction+-
- Compaction factor is applied for all base layers, driveway sub-base, and self-binding gravel.
- Compaction is set to 0% for single-size drainage gravel — compacting drainage gravel destroys its drainage performance.
- Compaction is set to 0% for loose decorative gravel and garden paths where no compaction is applied.
- Typical compaction factors: MOT Type 1 sub-base 15–25%, self-binding gravel 10–15%, hoggin 15–20%.
✓Wastage+-
- Wastage of at least 5% is added for all manually spread gravel.
- Irregular areas, curved edges, and sloped ground have wastage increased to 8–12%.
- Driveway applications include extra wastage for edge displacement and vehicle scatter — use 10%.
- The quantity including wastage — not the net coverage quantity — is used for ordering.
✓Before Purchase+-
- The coverage area result was cross-checked against the measured site area.
- Edging or gravel boards are in place or planned — uncontained gravel spreads beyond the intended area.
- A weed membrane is planned under decorative gravel — not required for drainage applications.
- Delivery vehicle access to the site was confirmed before ordering bulk gravel.
- Currency and units match the supplier quotation.
- Delivery charges and taxes were confirmed separately.
- Supplier delivery unit (bulk bag, loose load, tonne) matches the unit in the result.
Tips for Accurate Gravel Coverage
Always measure your edging area, not just the main surface
Gravel paths and borders lose material at their edges. Where gravel meets grass or planting beds without edging, assume 10–15% may migrate into the border zone over 6–12 months. Permanent steel, plastic, or timber edging reduces this loss and keeps depth more consistent.
Slate chip and decorative gravel cover more area per tonne
Lighter decorative gravels such as slate, marble, and golden flint have lower bulk density than crushed granite or roadbase. The same tonne can cover 25–30% more area, although decorative material may cost more per tonne.
For driveways, do not go below 50mm
At less than 50mm, driveway gravel displaces under tyre loading and exposes bare patches. Use a 50–75mm surface layer over a separately calculated compacted sub-base such as MOT Type 1 or crusher run.
A bulk bag covers roughly 10–14m² at 50mm
An 850kg bulk bag of common garden gravel at 1,500–1,600kg/m³ covers about 10.6–11.3m² at 50mm. Use this as a quick sense-check before relying on the detailed result.
Order by area, not by eye
A 1m × 1m patch at 50mm needs about 75–80kg. A 5m × 5m area at the same depth needs approximately 1.9 tonnes. The area-to-weight relationship is not intuitive, so calculate before ordering.
Decorative gravel settles over time
Fine decorative gravel and pea shingle can settle by 10–20% after traffic and rainfall. If you want a maintained 40mm surface after one season, laying about 50mm initially may be appropriate.
Calculator Limitations & Assumptions
- Bulk density is material-specific but not quarry-specific: Actual density varies by source quarry. For large areas (> 50 tonnes), ask your supplier for a tested bulk density and enter it using Custom.
- Depth assumes uniform laying: The calculator assumes uniform depth across the entire area. Uneven ground increases effective material requirement.
- Coverage area assumes rectangular calculation: For irregular shapes, break into sub-areas, calculate each, and sum totals. L-shaped and triangular areas can be entered using the Gravel Weight Calculator.
- Compaction not applied: Coverage calculators show loose-material coverage. For compacted layers (MOT Type 1, roadbase), the compacted depth will be 10–20% less than the loose depth. Use the Gravel Weight Calculator with compaction factor for precise sub-base ordering.
- Cost estimate excludes delivery and taxes: the estimate covers material cost only.