Sand Calculator
Estimate the sand needed for a paver bed, sandbox, sub-base or fill from a rectangle, a circle or a known area. The calculator returns the volume, the weight in tonnes and pounds, an optional bag count, and an optional total cost, with a waste allowance and a choice of sand types.
Formula
Worked example
A bed 5 m × 3 m at 5 cm deep is 15 m² × 0.05 m = 0.75 m³. Add 10% waste to 0.825 m³. At 1.6 t/m³ that is 0.825 × 1.6 = 1.32 tonnes, about 2,910 lb. In 50 lb bags that is ceil(1,320 ÷ 22.68) = 59 bags.
How the sand calculation works
Sand is sold by volume or by weight, so a reliable estimate starts with the volume of the space you want to fill. First the calculator works out the surface area: for a rectangle that is length times width, for a round area it is pi times the radius squared, and if you already know the area of an odd shape you can type it in directly. Multiplying that area by the depth of the sand layer gives the volume. The most common mistake is mixing units, so every dimension is converted to metres first, a depth typed as 5 cm becomes 0.05 m, which keeps the result honest. The volume is then shown in cubic metres, cubic yards and cubic feet so it matches however your supplier quotes.
Turning volume into tonnes, pounds and bags
Most aggregate yards sell sand by the tonne, so the volume is converted into weight using the material density, the mass packed into each cubic metre. Dry building sand is typically 1.5 to 1.7 tonnes per cubic metre, with 1.6 t/m³ a dependable default, while wet sand can exceed 1.9 t/m³ because water fills the gaps between grains. Pick the sand type to load a sensible density automatically, or choose Custom to enter your own. The weight is reported in tonnes, pounds and US tons, and if you are buying bagged sand you can switch on the bag count to see how many 40, 50 or 60 lb bags, 25 kg sacks or one tonne bulk bags the job needs.
Waste allowance, depth and cost
Sand compacts when it is screeded and rolled, some is lost to spillage and wind, and uneven ground swallows more than a flat plan suggests, so the calculator adds a waste allowance, ten percent by default, on top of the bare volume. Depth matters just as much as area: a screeded paver bed is only 2 to 5 cm, while a play sandbox is often 15 to 25 cm deep, and because depth multiplies the tonnage directly, doubling it doubles the sand you pay for. Switch on the cost estimate to price the order by the tonne, the US ton, the cubic yard or the bag. The total is a planning figure, local prices and delivery vary, so treat it as a guide and confirm the grade of sand before ordering.
Typical sand depths and densities
| Application or type | Typical value | Notes |
|---|---|---|
| Paver / block bedding layer | 2-5 cm (1-2 in) | Screeded level before laying |
| Children’s sandbox | 15-25 cm (6-10 in) | Use clean, washed play sand |
| Pipe / cable bedding | 10-15 cm (4-6 in) | Surrounds and protects services |
| Dry sand density | 1.5-1.7 t/m³ | Default 1.60 t/m³ used here |
| Wet sand density | 1.9-2.0 t/m³ | Heavier; water fills the voids |
Use these as starting points; your supplier can confirm the density of a specific sand.
Frequently asked questions
How many tonnes of sand are in a cubic metre?
Dry building sand weighs roughly 1.5 to 1.7 tonnes per cubic metre, so one cubic metre is about 1.6 tonnes on average. The exact figure depends on the grade of sand and how wet it is, wet sand can top 1.9 t/m³, which is why the calculator lets you pick the sand type or set a custom density.
How many bags of sand do I need?
Turn on the bag count and choose your bag size. The calculator divides the total weight by the bag weight and rounds up. As a rule of thumb a 50 lb bag holds about 0.5 cubic feet, so a cubic yard of sand is roughly 54 bags, but the exact number depends on the sand density and the depth you are filling.
How much extra sand should I order?
Add about 10% to the bare volume, which the waste allowance does for you. Sand compacts when it is screeded and rolled, some is lost to spillage and wind, and uneven ground swallows more than a flat plan suggests. The small surplus also lets you top up low spots later without arranging a second delivery.
Does the calculator work for circles and irregular areas?
Yes. Switch the shape to Circle and enter the diameter for a round area, and the calculator uses pi times the radius squared. For an irregular outline, split it into rectangles, total their areas and use the "I already know the area" option to enter that figure, then set the depth as usual.