Case 1
- Area to cover
- 10m²
- Layer depth
- 5cm
- Bulk density
- 1.5t/m³
0.75t
Open with these valuesGravel Calculator
0.75t
Result: 0.75 tArea × depth gives the volume, volume × bulk density gives the weight. 10 m² at 5 cm is 0.5 m³, and at 1.5 t/m³ that is 0.75 tonnes. Density is the uncertain part: loose stone runs from about 1.4 to 1.7 t/m³, so use the figure your supplier quotes when you have one.
The numbers at a glance
Held fixed: Area to cover 10.00 m², Layer depth 5.0 cm.
| Bulk density (t/m³) | Result (t) |
|---|---|
| 1.00 | 0.50 |
| 1.20 | 0.60 |
| 1.40 | 0.70 |
| 1.50Your value | 0.75 |
| 1.60 | 0.80 |
| 1.80 | 0.90 |
| 2.00 | 1.00 |
Worked examples
Case 2
- Area to cover
- 20m²
- Layer depth
- 10cm
- Bulk density
- 1.6t/m³
3.20t
Open with these valuesCase 3
- Area to cover
- 5m²
- Layer depth
- 5cm
- Bulk density
- 1.4t/m³
0.35t
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 in centimetres: about 5 cm for a bed, 7–10 cm to drive on.
- StepEnter the bulk density; loose gravel sits near 1.5 t/m³.
- ResultRead the weight, and order 5–10 % more for settling and handling.
What this number means
Density is the whole conversion
Area and depth are things you measure; the density is not. Loose stone runs from about 1.4 to 1.7 t/m³, and the same 0.5 m³ weighs 0.7 t at the bottom of that band and 0.85 t at the top. Use the figure your supplier quotes when you have one.
You order a weight, the area wants a volume
Suppliers price loose stone by the tonne, but what fills the area is a volume. Area × depth gives that volume, and the density is the only bridge between the two.
Wet or compacted stone arrives heavier
The 1.5 t/m³ default is the trade figure for loose, dry gravel. Wet or compacted material sits above it, so the same volume weighs more than the result says.
Where the 1.5 t/m³ default comes from
The source page behind this calculator gives 1.44 to 1.6 t/m³ for dry gravel. The 1.5 default is the trade rule of thumb inside that band, not a figure the page quotes on its own.
Commonly misread
The area needs 0.5 m³, so I ordered 0.5 tonnes.
Those are different units, and only the density connects them. At 1.5 t/m³ that 0.5 m³ is 0.75 tonnes, half as much again as you ordered.
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 layer, not 0.05.
The density is fixed at 1.5, so I left the field alone.
It is an input field, and stone type and compaction move it between roughly 1.4 and 1.7 t/m³. Across a 0.5 m³ order that spread is 0.15 tonnes, so enter your supplier's figure when you have one.
Reference table
| Area, depth, density | Volume | Tonnes |
|---|---|---|
| 5, 5, 1.4 | 0.25 m³ | 0.35 |
| 10, 5, 1.5 | 0.5 m³ | 0.75 |
| 15, 5, 1.5 | 0.75 m³ | 1.125 |
| 20, 10, 1.6 | 2 m³ | 3.2 |
| 30, 8, 1.7 | 2.4 m³ | 4.08 |
Questions
How much gravel do I need?
Multiply the area by the depth of the layer, then by the density. For 10 m² at 5 cm deep the volume is 0.5 m³, and at a typical 1.5 t/m³ that is 0.75 tonnes.
How deep should a gravel layer be?
It depends on use. A decorative bed or path usually needs about 5 cm, while a surface for walking or driving is firmer at 7–10 cm or more. Deeper layers spread weight and resist rutting.
What density should I enter?
Loose gravel is roughly 1.5 t/m³, which is the default here. The exact figure varies with stone type and compaction — pea gravel, crushed limestone and granite chippings typically fall between 1.4 and 1.7 t/m³.
Can I order by volume instead of weight?
Yes, suppliers sell both ways. The middle column of the table above is the volume for each row, and the weight is simply that volume multiplied by the density.
Should I order a little extra?
Yes. The result is the exact amount for the area and depth you enter, but gravel settles and compacts and some is always lost in handling. Around 5–10 % more is sensible, especially for a large or irregular area.
Sources and last check
Information, not professional advice.