Case 1
- Area to cover
- 20m²
- Layer depth
- 5cm
- Bulk density
- 1.6t/m³
1.60t
Open with these valuesSand Calculator
1.60t
Result: 1.60 tArea × depth gives the volume, volume × bulk density gives the weight. 20 m² at 5 cm is 1 m³, and at 1.6 t/m³ that is 1.6 tonnes — a bulk bag and a half. Sharp sand sits near 1.6 t/m³ and soft building sand near 1.5, both dry and loose; wet sand behaves differently.
The numbers at a glance
Held fixed: Area to cover 20.00 m², Layer depth 5.0 cm.
| Bulk density (t/m³) | Result (t) |
|---|---|
| 1.40 | 1.40 |
| 1.50 | 1.50 |
| 1.60Your value | 1.60 |
| 1.70 | 1.70 |
| 1.80 | 1.80 |
Worked examples
Case 2
- Area to cover
- 40m²
- Layer depth
- 4cm
- Bulk density
- 1.5t/m³
2.40t
Open with these valuesCase 3
- Area to cover
- 10m²
- Layer depth
- 30cm
- Bulk density
- 1.6t/m³
4.80t
Open with these valuesHow it's calculated
tonnes = area × depth × bulk density
- StepEnter the area in square metres — length × width for a rectangle.
- StepSet the depth: 3–5 cm for a paving bed, 20–30 cm for a sandpit.
- StepEnter the bulk density; dry loose sand sits between 1.5 and 1.6 t/m³.
- ResultRead the weight; a standard bulk bag is about one tonne.
What this number means
The default is dry, loose sand
The source table quotes 1.6 t/m³ for sharp sand and 1.5 for soft building sand, both as delivered dry and loose. Wet sand bulks up in the heap while weighing more per cubic metre, so neither figure survives a rained-on stockpile.
A bulk bag is roughly a tonne
Suppliers sell sand loose by the tonne and bagged in one-tonne bulk bags, so the result is close to a bag count. At 1.6 t/m³ one bag holds about 0.63 m³.
Where the 1.6 t/m³ default comes from
The coverage table behind this calculator lists sharp/grit sand at 1.6 t/m³, covering 12.5 m² per tonne at 50 mm. EN 1991-1-1 Table A.6 gives dry sand as 15 to 16 kN/m³, about 1.53 to 1.63 t/m³, which brackets it.
Sharp sand and soft sand are not interchangeable
Sharp or grit sand is coarse and drains, which is what a paving or slab bed needs. Soft building sand is fine and is for mortar, and it is also the lighter of the two at 1.5 t/m³.
Commonly misread
The bed needs 1 m³, so I ordered 1 tonne.
Those are different units, and only the bulk density connects them. At 1.6 t/m³ that cubic metre is 1.6 tonnes, well over a single bulk bag.
I entered the layer depth in metres.
Depth is in centimetres here while the area is in square metres. Enter 5 for a 5 cm bed, not 0.05.
The sand got rained on, but a tonne is still a tonne.
It is, and that is the problem: part of what you paid for is water. Wet sand also bulks in the heap, so the same weight neither fills nor spreads the way the dry figure says.
Reference table
| Area, depth, density | Volume | Tonnes |
|---|---|---|
| 10, 5, 1.6 | 0.5 m³ | 0.8 |
| 12.5, 5, 1.6 | 0.625 m³ | 1 |
| 20, 5, 1.6 | 1 m³ | 1.6 |
| 20, 10, 1.6 | 2 m³ | 3.2 |
| 50, 5, 1.6 | 2.5 m³ | 4 |
Questions
How much sand do I need?
Multiply the area by the depth of the layer, then by the bulk density. For 20 m² at 5 cm the volume is 1 m³, and at 1.6 t/m³ that is 1.6 tonnes.
How many square metres does a tonne of sand cover?
The source table gives 12.5 m² per tonne at 50 mm for sharp sand and 13.3 m² per tonne for soft building sand. At 100 mm both halve, to roughly 6 m² per tonne.
What bulk density should I enter?
Dry loose sand sits between 1.5 and 1.6 t/m³, and 1.6 is the default here. Damp or compacted sand runs higher, so use the density on your delivery note when you have one.
How deep should a sand layer be?
It depends on the job. A bedding layer under paving slabs or block paving is usually 3 to 5 cm, a levelling course under a shed base 5 to 10 cm, and a children's sandpit 20 to 30 cm.
How many bulk bags is that?
A standard bulk bag holds about one tonne, so the result in tonnes is close to the number of bags. Bags are sold whole, so round up and expect a little settling in transit.
Sources and last check
Information, not professional advice.