Rendering Sand Coverage Calculator(Scratch & Finish Coats)

Calculate rendering sand wall coverage.

Estimate rendering sand coverage for scratch and finish coats with coat-specific depth and wastage.

🕒 Last updated: August 20, 2026

Inputs

Sand Type & Application

Bulk Density (kg/m³)

ℹ️Auto-filled by material. Replace with supplier-tested density when available.

Target Area

Depth / Thickness

Bag Size for Results

▾

Quantity to Order (incl. 12% wastage)

1.06 tonnes

1,062 kg

Loose material order quantity

Number of Bags

43 bags

2 × 850kg bulk bags

Rounded up to complete bags

✓ 12.0mm is within the recommended range of 10–12mm.

Material: Rendering sand (scratch coat)

Density: 1,580 kg/m³

Wastage: 12% included

Coverage Visualizations

Coverage Area

Layer Depth Cross-Section

Practical Coverage at 12.0mm Depth

After 12% wastage

1 × 25kg bag

1.2 m²

1 × 850kg bulk bag

40.0 m²

1 tonne

47.1 m²

2 tonnes

94.2 m²

Your quantity

50.0 m²

Bag Count Visualizer

BAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAGBAG

More sand coverage calculators

More sand coverage calculators+

More sand coverage calculators-

Paving Sand Coverage Calculator Floor Screed Sand Calculator Plastering Sand Coverage Calculator Sharp Sand Coverage Calculator Bulk Bag Sand Coverage Calculator Play Sand CalculatorRendering Sand Coverage Calculator(this page)Lawn Top Dressing Sand Calculator

Construction Knowledge Base(70 guides)+

Knowledge Guides — 70 Articles

View all resources →

Concrete21 Material7 Brick8 Cement & Mortar5 Steel6 Land & Earthwork4 Painting4 Finishing4 Tiles10 Plumbing1

Rendering sand by wall area and coat

Scratch and finish coats use different thicknesses and should be estimated separately.

Rendering waste is higher because of droppings and handling.

Default wastage: 12%.
Measure net wall area.
Calculate cement and additives separately.

How Is Sand Coverage Calculated?

Sand coverage is calculated from area, layer depth, bulk density, and wastage allowance. The calculator first converts the required sand layer into volume, then converts that volume into weight using the selected sand density.

Use FIND QUANTITY when you know the area and depth and want to calculate tonnes or bags. Use FIND AREA when you already have a quantity and want to know how far it will spread. Use FIND DEPTH when you know the quantity and area and want to check the achievable layer thickness.

Step 1 — Convert depth to metres

Depth (m) = Depth (mm) / 1,000

Depth must be converted into metres before calculating volume. For example, a 25 mm paving bed is 25 / 1,000 = 0.025 m deep.

Step 2 — Calculate sand volume

Volume (m³) = Area (m²) × Depth (m)

If the area is 20 m² and the required sand depth is 25 mm, the depth is 0.025 m. The required volume is 20 × 0.025 = 0.500 m³.

Step 3 — Convert volume into mass

Mass (kg) = Volume (m³) × Bulk Density (kg/m³)

Sand is commonly ordered by weight. If the volume is 0.500 m³ and the selected sand density is 1,800 kg/m³, the base quantity is 0.500 × 1,800 = 900 kg.

Step 4 — Add wastage when calculating order quantity

Order Mass = Base Mass × (1 + Wastage / 100)

Wastage covers mixing loss, levelling, spreading, uneven surfaces, plaster droppings, and small measurement errors. With 5% wastage, 900 kg becomes 900 × 1.05 = 945 kg.

Step 5 — Calculate coverage area when quantity is fixed

Coverage Area = Supplied Mass / [Density × Depth × (1 + Wastage / 100)]

When the available sand quantity is fixed, wastage reduces the practical coverage area. For example, 1,000 kg of sand at 1,800 kg/m³ and 25 mm depth covers 22.2 m² before wastage, but only about 21.2 m² with 5% wastage.

Step 6 — Calculate achievable depth from quantity and area

Depth (m) = Supplied Mass / [Area × Density × (1 + Wastage / 100)]

This mode checks how thick a layer can be achieved from a known sand quantity. After calculating depth in metres, multiply by 1,000 to convert the result into millimetres.

Optional — Damp-sand bulking correction

Dry-equivalent Volume = Measured Damp Volume / (1 + Bulking / 100)

Use bulking correction only when damp sand is measured by apparent volume on site, such as by boxes or buckets. Weight-based supplier orders in kg, tonnes, or bags normally do not require this correction.

Worked Sand Coverage Examples

The examples below show how to enter real site measurements into the sand 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 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 Sharp Sand Required for Paving Bedding

Calculator mode: FIND QUANTITY

A patio is 4 m wide and 5 m long. The paving bedding layer is 25 mm thick. The selected material is sharp sand with an assumed loose bulk density of 1,800 kg/m³. A 5% wastage allowance is added for levelling, spreading loss, and small surface 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 area and depth are known, and the calculator must find how much sand to order.
Material	Sharp sand	Commonly used for paving bedding and screed-type bedding layers.
Bulk density	1,800 kg/m³	Used to convert bedding volume into sand weight.
Length	5 m	Patio length.
Width	4 m	Patio width.
Depth	25 mm	Bedding layer thickness.
Wastage	5%	Allows for levelling and spreading loss.
Bag size	25 kg 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	5 × 4 = 20.00 m²
Convert depth to metres	Depth (m) = Depth (mm) / 1,000	25 / 1,000 = 0.025 m
Calculate sand volume	Volume = Area × Depth	20.00 × 0.025 = 0.500 m³
Convert volume to mass	Mass = Volume × Density	0.500 × 1,800 = 900 kg
Add wastage	Order Mass = Base Mass × 1.05	900 × 1.05 = 945 kg
Convert to tonnes	Tonnes = kg / 1,000	945 / 1,000 = 0.95 tonnes
Convert to 25 kg bags	Bags = Order Mass / Bag Size	945 / 25 = 37.8 bags → order 38 bags

Result

The paving bedding layer requires about 945 kg of sharp sand after wastage. That is approximately 0.95 tonnes, or 38 × 25 kg bags.

Practical note

For paving work, keep the bedding layer consistent. A 5 mm increase in bedding depth across a 20 m² patio adds 0.10 m³ of sand, which is about 180 kg at this density.

Example 2 — Calculate Floor Screed Sand Quantity

Calculator mode: FIND QUANTITY

A floor screed area is 48 m² and the screed thickness is 50 mm. The selected sand has an assumed bulk density of 1,750 kg/m³. A 5% wastage allowance is included for mixing, spreading, and level correction.

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 floor area and screed thickness are known.
Material	Screed sand	Used for cement-sand floor screed.
Bulk density	1,750 kg/m³	Typical estimate for screeding sand.
Area	48 m²	Measured floor area.
Depth	50 mm	Screed thickness.
Wastage	5%	Allows for mixing loss and level variation.
Bag size	25 kg bag	Useful if ordering bagged material.

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
Use measured area	Area = 48 m²	48.00 m²
Convert depth to metres	Depth (m) = Depth (mm) / 1,000	50 / 1,000 = 0.05 m
Calculate screed sand volume	Volume = Area × Depth	48.00 × 0.05 = 2.40 m³
Convert volume to mass	Mass = Volume × Density	2.40 × 1,750 = 4,200 kg
Add wastage	Order Mass = Base Mass × 1.05	4,200 × 1.05 = 4,410 kg
Convert to tonnes	Tonnes = kg / 1,000	4,410 / 1,000 = 4.41 tonnes
Convert to 25 kg bags	Bags = Order Mass / Bag Size	4,410 / 25 = 176.4 bags → order 177 bags

Result

The floor screed requires about 4.41 tonnes of sand after wastage. If using 25 kg bags, this is approximately 177 bags.

Practical note

For screed work, confirm whether the calculator is estimating sand only or the complete screed mix. Cement, water, admixture, and mix ratio should be calculated separately.

Example 3 — Check How Much Wall Area One Bulk Bag Covers for Plastering

Calculator mode: FIND AREA

A user has one 850 kg bulk bag of plastering sand and wants to know how much wall area it can cover at 12 mm plaster thickness. The assumed bulk density is 1,580 kg/m³. A 12% allowance is applied for mixing loss, wall unevenness, and plaster droppings.

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 sand quantity and plaster thickness are known, and the calculator must find coverage area.
Material	Plastering sand	Fine sand suitable for plastering work.
Bulk density	1,580 kg/m³	Used to convert the 850 kg bag into volume.
Quantity	850 kg	One bulk bag.
Depth	12 mm	Plaster thickness.
Wastage / allowance	12%	Reduces practical wall coverage.

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 / 1,580 = 0.538 m³
Convert depth to metres	Depth (m) = Depth (mm) / 1,000	12 / 1,000 = 0.012 m
Coverage before wastage	Coverage = Volume / Depth	0.538 / 0.012 = 44.83 m²
Apply wastage allowance	Usable Coverage = Base Coverage / 1.12	44.83 / 1.12 = 40.03 m²

Result

One 850 kg bulk bag of plastering sand covers about 44.8 m² at 12 mm thickness before wastage. With a 12% practical allowance, use about 40 m² as the safer coverage estimate.

Practical note

Plastering sand coverage is affected by wall flatness. Rough blockwork, uneven brickwork, and rework can increase sand consumption significantly.

Example 4 — Calculate Play Sand Required for a Sandpit

Calculator mode: FIND QUANTITY

A sandpit is 6 ft long and 8 ft wide. The user wants to fill it to 6 inches deep using play sand with an assumed density of 1,550 kg/m³. A 5% allowance is added for settlement and levelling.

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 sandpit area and fill depth are known.
Material	Play sand	Washed sand used for children’s play areas and sandpits.
Bulk density	1,550 kg/m³	Used to convert sand volume into weight.
Length	8 ft	Sandpit length.
Width	6 ft	Sandpit width.
Depth	6 in	Required fill depth.
Wastage / allowance	5%	Allows for settlement and levelling.

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	8 × 6 = 48 ft²
Convert area to m²	Area (m²) = Area (ft²) × 0.092903	48 × 0.092903 = 4.46 m²
Convert depth to metres	Depth (m) = Depth (in) × 0.0254	6 × 0.0254 = 0.152 m
Calculate sand volume	Volume = Area × Depth	4.46 × 0.152 = 0.679 m³
Convert volume to mass	Mass = Volume × Density	0.679 × 1,550 = 1,053 kg
Add allowance	Order Mass = Base Mass × 1.05	1,053 × 1.05 = 1,106 kg
Convert to tonnes	Tonnes = kg / 1,000	1,106 / 1,000 = 1.11 tonnes

Result

The sandpit requires about 1,053 kg of play sand before wastage, or about 1.11 tonnes after a 5% allowance.

Practical note

For play areas, check that the sand is sold as washed play sand, not sharp sand or building sand. Material suitability matters as much as quantity.

Example 5 — Check Achievable Sand Depth from a Fixed Quantity

Calculator mode: FIND DEPTH

A user has 1 tonne of sharp sand and wants to spread it over a 20 m² area. The selected sand density is 1,800 kg/m³. A 5% allowance is applied to estimate the practical finished depth.

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 sand quantity and area are known, and the calculator must find achievable depth.
Material	Sharp sand	Dense sand commonly used for bedding and screeding.
Bulk density	1,800 kg/m³	Used to convert mass into volume.
Quantity	1 tonne	Available sand quantity.
Area	20 m²	Area to cover.
Wastage / allowance	5%	Used to estimate practical depth after spreading and levelling.

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 tonnes to kg	Mass = Tonnes × 1,000	1 × 1,000 = 1,000 kg
Calculate available volume	Volume = Mass / Density	1,000 / 1,800 = 0.556 m³
Use measured area	Area = 20 m²	20.00 m²
Calculate depth in metres	Depth = Volume / Area	0.556 / 20.00 = 0.0278 m
Convert depth to mm	Depth (mm) = Depth (m) × 1,000	0.0278 × 1,000 = 27.8 mm
Apply 5% allowance	Practical Depth = Base Depth / 1.05	27.8 / 1.05 = 26.5 mm

Result

One tonne of sharp sand spread over 20 m² gives about 27.8 mm depth before allowance, or about 26.5 mm practical depth after a 5% allowance.

Practical note

This mode is useful when material is already available on site and the user wants to check whether it can achieve the required layer thickness.

Calculator Limitations & Assumptions

Plaster and render coverage is for sand only: The calculator gives sand quantity only. For the complete plastering mix you also need cement (and lime). Use the Mix Design Calculator for full plastering material quantities.
Depth assumes a perfectly level surface: For floor screeds, any variation in base level (high spots, low spots) means the average depth exceeds the nominal depth. Budget 5–10% extra for floor screed on uneven bases.
Play-sand density varies: Play sand (washed and graded) is lighter and more variable than construction sand. The calculator uses 1,550 kg/m³ as a representative value; actual density can range from 1,450–1,650 kg/m³.
Bulking correction is approximate: The correction uses typical bulking factors. Actual bulking depends on exact moisture content and particle size distribution.
Wall coverage assumes a flat substrate: Uneven brickwork, deep joints, or rough blockwork requires more material to achieve a flat coat.

Disclaimer: This calculator provides approximate results for planning and estimation purposes only. Actual requirements may vary based on site conditions, materials, workmanship, and local building regulations. Always consult a qualified engineer, architect, or construction professional before making final decisions.

FAQ

The scratch coat is the base render layer (typically 10-12mm) that bonds to the wall and is scored to key the next coat; the finish coat (6-8mm) is the thinner top layer for final appearance — calculate each with its own depth.

External rendering has significant material loss from droppings, scaffolding handling, and weather exposure during application — higher than the 5% typical for internal work, so this page defaults to 12%.

No — this calculates sand quantity only. Cement, lime, and any waterproofing or bonding additives need to be calculated separately according to your render specification.

It depends heavily on the application and depth. For paving bedding at 25mm using sharp sand at 1,800kg/m³, 1 tonne covers 22.2m². For plastering at 12mm using plastering sand at 1,580kg/m³, 1 tonne covers approximately 52.6m² of wall. The reference table shows coverage per tonne for every sand type at five standard depths.

A paved patio normally uses a 25mm sharp-sand bedding layer. At 25mm and 1,800kg/m³, coverage per tonne is 22.2m². For a 20m² patio, 20 ÷ 22.2 = 0.9 tonnes; with 5% wastage, order approximately 945kg or 38 × 25kg bags. This is bedding only; sub-base material and pavers are separate.

A standard 850kg bulk bag of screeding sand at 1,750kg/m³ and 50mm depth covers 850 ÷ (1,750 × 0.05) = 9.7m². At 75mm depth, coverage drops to 850 ÷ (1,750 × 0.075) = 6.5m².

No. Paving bedding requires sharp sand, which is coarse and angular for compaction and stability. Plastering requires soft building or plastering sand, which is fine and smooth for workability and finish. Sharp sand produces a coarse plaster finish, while building sand creates an unstable paving bed that settles under load.

Measure the sandpit length and width and choose a depth, typically 100–200mm. For a 1.5m × 1.5m sandpit at 150mm depth: 1.5 × 1.5 × 0.15 × 1,550 = approximately 523kg, or about 21 × 25kg bags. Find Depth mode can verify how deep an available number of bags will fill the sandpit.

Bulking is the increase in apparent volume when sand is damp — fine damp sand can expand 25-40% in volume. Turn on the bulking correction only if you measured a damp sand quantity by apparent volume (bucket, box, or wheelbarrow count). If you're ordering by weight (kg, tonnes, or bags), bulking correction is not needed.

FIND QUANTITY answers 'how much sand do I need?' from a known area and depth. FIND AREA answers 'how far will this sand go?' from a known quantity and depth. FIND DEPTH answers 'how thick a layer can I achieve?' from a known quantity and area — useful when material is already on site.

No — this calculator estimates sand quantity only. For a complete plastering or mortar mix including cement (and lime where used), use the Sand Calculator with a mix ratio, or the Concrete Mix Design Calculator.

5% is a reasonable minimum for machine-spread or carefully handled sand. Increase to 8-12% for plastering, rendering, and hand-applied work where droppings and mixing loss are higher, and for irregular or curved areas with more edge loss.

Sand density varies meaningfully by type and application — sharp sand (~1,800 kg/m³) is significantly denser than plastering sand (~1,580 kg/m³) or play sand (~1,550 kg/m³). Using the wrong density can make a coverage estimate 10-15% wrong, which matters for bedding layers with tight tolerances.