Sand Calculator
Find how many tonnes and bulk bags of sharp or building sand you need.
Measure your project
Your answer
That is 0.60 m³.
If you buy bags
If you buy bulk bags
What it costs
Sharp sand: £75 a bulk bag with VAT, the middle of only 3 UK sellers (Oct 2026). Building sand: about £67.35. Treat both as rough guides.
Quick answers
- A 4 × 3 m bed, 50 mm deep
- About 0.91 tonnes. You would need 2 bulk bags of 800 kg.
- Weight of 1 m³
- About 1.51 tonnes for sharp or building sand, from Wickes's cover figure.
- Bed under block paving
- 50 mm of sand, says Interpave. That is about 76 kg per m².
- Small bags
- Wickes Major Bags hold 20 kg. 50 of them make a tonne.
- Bricks per bulk bag
- A bulk bag of building sand lays about 900 bricks, says Heidelberg.
How to work it out
- Find the area: length × width, both in metres.
- Choose the depth of sand in mm, then change it to metres (÷ 1,000).
- Area × depth = cubic metres of sand.
- Sharp and building sand both weigh about 1.51 tonnes per m³. Multiply to get tonnes.
- For bulk bags, divide the tonnes by 0.8 and round up.
4 × 3 × 0.05 = 0.6 m³
0.6 × 1.51 = 0.91 tonnes
0.91 ÷ 0.8 = 1.1 → 2 bags
Sand for common sizes, 50 mm deep
Each row shows one area with a 50 mm sand bed. That is the depth Interpave gives under block paving.
| Size | Tonnes | 800 kg bags | 20 kg bags |
|---|---|---|---|
| 2 × 2 m | 0.30 | 1 | 16 |
| 3 × 3 m | 0.68 | 1 | 34 |
| 4 × 3 m | 0.91 | 2 | 46 |
| 5 × 4 m | 1.51 | 2 | 76 |
| 6 × 5 m | 2.27 | 3 | 114 |
| 10 × 5 m | 3.78 | 5 | 189 |
Flat ground, nothing extra. Bag counts are rounded up.
For 25 mm, use half these tonnes. For 100 mm, use twice as many.
Sand cover per tonne and per bag
Wickes gives 10.6 m² per 800 kg bag of sand at 50 mm deep. From that, each m³ of sand weighs about 1.51 tonnes. The table below uses it.
| Depth | 1 tonne | 800 kg bag | 20 kg bag |
|---|---|---|---|
| 25 mm | 26.5 m² | 21.2 m² | 0.53 m² |
| 50 mm | 13.2 m² | 10.6 m² | 0.26 m² |
| 75 mm | 8.8 m² | 7.1 m² | 0.18 m² |
| 100 mm | 6.6 m² | 5.3 m² | 0.13 m² |
Sharp sand or building sand?
Wickes gives both the same cover per bulk bag. So both weigh about 1.51 tonnes per m³, and this calculator works for either.
Building sand
Building sand goes in mortar for laying bricks. Some sellers call it soft sand. Heidelberg says a bulk bag lays about 900 bricks.
Gilmore Building Supplies gives a common bricklaying mix: 5 parts building sand to 1 part cement.
Sharp sand
Sharp sand goes in concrete, mixed with cement and gravel. That is how the Concrete Society's DIY mix table uses it.
The same table puts sharp sand in bedding mortar for paving slabs: 1 part cement to 4 parts sharp sand.
Prices
- Sharp sand: £75 a bulk bag, the middle of only 3 sellers (lowest £50.40, highest £77.24).
- Building sand: £67.35, the middle of 4 prices from 3 sellers (lowest £50.40, highest £77.26).
With so few sellers, treat both as a rough guide. Prices include VAT. Weigh up bag size too: Wickes bags are 800 kg, Tippers bags 850 kg or more.
Sand under block paving
Interpave, the UK paving makers' group, gives these layers for drives, paths and patios.
| Layer | Depth |
|---|---|
| Concrete blocks | at least 50 mm |
| Sand bed (laying course) | 50 mm |
| Sub-base | up to 200 mm, by ground |
Softer ground needs a deeper sub-base.
Work out the sand here. If your sub-base is Type 1, our Type 1 calculator works that out.
Laying a drive? Check your local building rules or ask a builder or engineer.
Before you order sand
- Measure each area in metres. Add more areas in the calculator if your space is an odd shape.
- Pick the depth. Use 50 mm for a bed under block paving.
- Choose sharp or building sand. Ask your merchant if you are not sure.
- Check the bag weight. Is it 800 kg, 850 kg or something else?
- Ask for the price with VAT and delivery.
- Plan where the lorry can drop a bulk bag. Small bags are easier to carry in a car.
Questions people ask
How much sand do I need?
Use the calculator above, or work it out by hand. m² × depth in metres × 1.51 = tonnes of sand.
How much sand do I need under block paving?
Interpave sets a sand bed of 50 mm. That is about 76 kg per m². A 4 × 3 m area needs about 0.91 tonnes.
How many cubic metres are in a tonne of sand?
Divide 1 by 1.51: about 0.66 m³. As a 50 mm bed, that much sand covers about 13.2 m².
How much sand is in a bulk bag?
By weight, 800 kg at Wickes, or 850 kg and up at Tippers. By volume, an 800 kg bag holds about 0.53 m³.
How many bags of sand are in a tonne?
50 Major Bags of 20 kg make a tonne. An 800 kg bulk bag weighs the same as 40 of them.
How do I work out the weight of sand?
Multiply the m³ by 1.51 to get tonnes. A 4 × 3 m bed at 50 mm is 0.6 m³, so it weighs about 0.91 tonnes.
How much is a bulk bag of sand?
Sharp sand is about £75 and building sand about £67.35, with VAT. Each is from only 3 sellers, so treat them as rough guides.
How many bricks will a bulk bag of building sand lay?
About 900 bricks, says Heidelberg Materials' building sand data sheet.
Where our numbers come from
- Sand weight: Wickes sharp sand bulk bag (800 kg covers 10.6 m² at 50 mm)
- Building sand weight: Wickes building sand bulk bag
- Small bags: Wickes Major Bags (20 kg sand, 22.5 kg gravel)
- 850 kg bulk bags: Tippers aggregates list
- Bulk bag prices: the middle price from 3 UK sellers each (Wickes, Tippers, Lawsons; Oct 2026)
- Sub-base by ground: Interpave, Concrete Block Paving
- Bricks per bulk bag: Heidelberg building sand data sheet (about 900)
- Mix ratios and cement per bulk bag: Gilmore Building Supplies guide
- DIY mixes: Concrete Society, Batching by volume
Made by BuildersCount. Last checked 3 Oct 2026.
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