About the Sand Calculator
Sand turns up in almost every outdoor job: the bed under a patio of pavers, the level base under an above-ground pool, the filling for a child's sandpit, the joints between blocks. Each needs a different depth, and sand is usually sold by weight while the job is measured by area — which is where the arithmetic goes wrong.
This sand calculator takes the area and the depth, adds a waste allowance, and turns the volume into the weight suppliers sell by, in US tons or metric tonnes. It also shows the volume in cubic yards or cubic metres, the number of bags, and an optional cost. Because wet sand weighs more than dry sand, you choose how damp the sand will be, and the calculator shows how much of the weight is water.
How to Use the Sand Calculator
Choose feet and inches or metres and millimetres.
Choose a rectangle or a circle. Enter the length and width, or the diameter for a round pool base.
Enter the depth of sand in inches or millimetres.
Choose whether the sand is dry, damp as usually delivered, or wet.
Leave the waste allowance at 10%, which covers screeding off the excess and filling low spots.
Optionally, add the price per ton or tonne.
How Much Sand: the Formula
area = length × width (or π × diameter² ÷ 4)
volume = area × depth × (1 + waste %)
weight = volume × bulk densityThe calculation is done in metres and converted back at the end, so an inch of bedding sand is treated as a twelfth of a foot rather than a tenth.
Step-by-Step Example
A 12 by 10 foot patio of pavers on a 1-inch bed of dry sand.
Area: 12 × 10 = 120 ft² (11.15 m²)
Depth: 1 in = 0.0833 ft (0.025 m)
Volume: 120 × 0.0833 = 10.0 ft³ (0.283 m³)
With waste: 10.0 × 1.10 = 11.0 ft³ = 0.41 yd³
Weight: 0.311 m³ × 1.6 t/m³ = 0.50 t = 0.55 US tons
Bags: 1,099 lb ÷ 50 lb = 22 bagsIn metric, a 4 by 3 metre patio on 30 mm of damp sand is 0.40 m³ with 10% extra, about 0.69 tonnes. At 45 per tonne that is about 31.
How Deep Should the Sand Be?
| Use | Typical depth |
|---|---|
| Bedding under pavers or slabs | 1 in / 25–30 mm |
| Base under an above-ground pool | 2 in / 50 mm |
| Sandpit or sandbox | 8–12 in / 200–300 mm |
Paver bedding should be thin and even. A deep sand bed moves under load and the pavers sink unevenly, so levels are set in the compacted sub-base below, not by adding sand.
How Much Does Sand Weigh?
| Condition | t/m³ | US tons per yd³ |
|---|---|---|
| Dry sand | about 1.6 | about 1.35 |
| Damp sand, as delivered | about 1.75 | about 1.48 |
| Wet sand | about 1.9 | about 1.60 |
Water fills the gaps between grains, adding weight but little volume. Sand bought by the tonne while damp therefore contains some water you are paying for, and a trailer that carries a tonne of dry sand may be overloaded by the same volume of wet sand.
Choosing the Right Sand
Sharp sand (also called concrete or grit sand) has angular grains that lock together when compacted. It is the right choice for paver bedding and pool bases.
Soft building sand is finer and rounder. It is for mortar, not for bedding.
Washed play sand is screened and cleaned for sandpits, so it does not stain clothes or turn to mud.
Jointing sand is very fine, sometimes with a polymer binder, for brushing into the gaps between pavers after they are laid.
Preparing the Bed Before the Sand
The sand is the last thin layer, so the work that decides whether a patio stays flat happens underneath it.
Dig out to the right depth. For a garden patio that is usually the paver thickness, plus the sand bed, plus 4 inches (100 mm) of sub-base. Driveways need a deeper sub-base.
Compact the sub-base in layers. Crushed stone or Type 1 should be rolled or plate-compacted every couple of inches, with a slight fall of about 1 in 60 so rain runs off the finished surface.
Screed the sand, do not trowel it. Lay two straight rails, fill between them with sand, and draw a straight board along the rails to leave an even bed. Do not walk on the screeded sand; lay the pavers from the side already laid.
Compact once the pavers are down. A plate compactor with a rubber mat beds the pavers into the sand and pushes jointing sand into the gaps.
Understanding Your Result
Sand needed is the headline weight in tons or tonnes.
Weight repeats it in pounds or kilograms.
Volume gives cubic yards and cubic feet, or cubic metres and litres, with the waste included.
Area and depth shows the numbers used, which is worth checking for thin beds.
Bags gives 50 lb bags, or 25 kg and bulk bags in metric.
Cost multiplies the weight by your price.
Worth knowing lists the usual depths and, for damp or wet sand, what the same volume would weigh dry.
When Should You Use This Calculator?
Laying a patio or path of pavers, to order the bedding sand.
Preparing a base for an above-ground pool.
Filling a sandpit or sandbox for children.
Checking a trailer load, where the weight of wet sand matters.
Comparing prices quoted per ton, per tonne or per bulk bag.
Common Mistakes
Treating an inch as 0.1 feet. It is 0.083 feet, and the error adds 20%.
Levelling with sand. Deep sand beds let pavers sink; get the levels right in the sub-base.
Ignoring moisture. Wet sand weighs noticeably more than dry for the same space.
Using soft sand under pavers. Sharp sand compacts; soft sand does not.
Forgetting the jointing sand for the gaps once the pavers are down.