How much sand do I need?

1. The calculation, step by step

Sand is a pure volume problem — you are filling a rectangular space, so the amount you need is area multiplied by depth. Convert everything to the same unit before you multiply.

1. Measure the area. Length × width in metres gives square metres.
2. Convert depth to the same unit. Divide millimetres by 1,000 to get metres — 100 mm = 0.1 m.
3. Volume in cubic metres metres × metres × metres = cubic metres directly.
4. Count bags. Divide the volume in m³ by your bag size in m³ (a 25 kg bag of play sand ≈ 0.0164 m³), then round up.

Worked example — a 2 m × 2 m sandpit at 100 mm deep: 2 × 2 × 0.1 = 0.4 m³. Weight = 0.4 × 1,520 = 608 kg. Bags: 608 ÷ 25 = 24.3, so order 25 bags of 25 kg play sand.

2. Sandpit size reference table

These figures use play sand at 1,520 kg/m³. Bag counts are rounded up; add 5–10% extra if the base is uneven.

At 100 mm — standard sandpit fill depth

At 150 mm — deeper fill for older children

Volumes rounded to 3 decimal places; bag counts rounded up from exact weight ÷ 25 kg.

3. Types of sand and what they are used for

Not all sand is the same. Choosing the wrong type is the most common buying mistake — the right sand for a mortar joint is not what you want in a sandpit, and the sand you lay pavers on is different again. Here is a plain-English summary.

• Play sand is the only type suitable for a sandpit. It has been washed and sieved to remove sharp edges, oversized particles and dust, making it safe for children to handle. It is typically fine-grained and pale in colour. Density: approximately 1,520 kg/m³.
• Builder's sand / all-purpose sand is a general-purpose material for levelling, bedding, backfill, and mixing into soil or compost. It is coarser than play sand and not recommended for sandpits. Density: approximately 1,600 kg/m³.
• Mason sand / fine sand is very finely graded — used in mortar for brickwork and blockwork, in render, and around pool installations. It compacts well and gives a smooth finish. Density: approximately 1,600 kg/m³.
• Sharp sand / concrete sand is coarser and more angular than mason sand — the angular particles lock together, which is exactly what you need in a concrete mix or as a compactable bedding layer under pavers and slabs. Density: approximately 1,680 kg/m³.

As a general rule: use play sand for children, mason sand for mortar and renders, and sharp sand for concrete mixes and paver bases. All-purpose sand fills the gaps in between — useful on the job site but not the best choice for any one specific application.

4. Sand for paving — bedding-layer depths

A compacted sand bedding layer is commonly laid under concrete pavers and natural stone slabs to allow fine levelling before the surface is set. The widely-used guideline is a 25–40 mm layer of sharp sand or concrete sand, compacted and screeded level before placing the pavers. This is a typical practice guideline — always follow your paver manufacturer's installation instructions and your local authority's guidance for driveways and load-bearing surfaces.

Uses concrete sand density (1,680 kg/m³). Bag counts rounded up.

5. Bags, bulk bags or loose delivery?

The sand volume is the same whether it comes in bags or by the lorry — the choice is about handling, access and cost.

• Bags are the practical choice for small jobs — up to about 0.3 m³. They are easy to carry through a gate, store in a garage and measure out accurately.
• Bulk or jumbo bags ("dumpy bags") typically hold 0.5–1 m³ (500–1,000 kg). They sit on a pallet, need fork-truck access to move, and cost less per kg than individual bags.
• Loose bulk delivery is the cheapest per tonne but requires a flat, accessible tip point and a way to move the pile — usually a wheelbarrow or loader. For large jobs (one cubic metre or more), bulk is almost always the most economical option.

For sandpits specifically, bags are usually the best choice — play sand is only sold bagged at most hardware stores, and the quantities involved (less than half a cubic metre for most residential sandpits) do not justify a bulk delivery. The calculator shows bag count alongside the volume so you can compare both options directly.

Common questions

How much sand do I need for a sandbox?

Measure the inside in feet: length × width × depth (in feet) = cubic feet; divide by 27 for cubic yards. A 6 ft × 6 ft sandbox at 4 inches deep needs 12 cubic feet — roughly 23 standard 50 lb bags of play sand, or about 0.45 cubic yards in bulk. The calculator on this page handles any size in one step.

How many 50 lb bags of sand do I need?

Find your volume in cubic feet (length × width × depth, all in feet). Play sand weighs about 95 lb per cubic foot, so a 50 lb bag covers roughly 0.53 cubic feet. Divide your cubic feet by 0.53 and round up. Example: 10 ft³ ÷ 0.53 = 18.9, so order 19 bags.

How much does a yard of sand weigh?

A cubic yard of dry play sand weighs roughly 2,550 lb (about 1.28 short tons). Coarser concrete or sharp sand runs around 2,800 lb/yd³ (1.40 tons). Always check with your supplier — delivered sand often contains moisture, which can add hundreds of pounds per yard to the actual load.

How deep should sand be in a sandbox?

3–6 inches (75–150 mm) is the widely-used guideline for a play sandbox. Three inches is enough for basic play and lets the sandbox drain quickly after rain. Six inches gives more room to dig and mould, but roughly doubles the amount of sand (and the weight) — so factor that into your order.