How to use the gravel calculator
- Choose the material. Each has a typical density, which converts volume into weight.
- Enter the length, width and finished depth of the area.
- Keep about 10% extra for loose gravel, or 10–20% for sub-base that will be compacted.
- Order by weight (tons or tonnes) from a quarry or merchant, or by volume if that is how they sell it.
The gravel formula
Volume = length × width × depth Weight = volume × density US tons = pounds ÷ 2,000 Tonnes = kilograms ÷ 1,000
Worked example (US)
A 20 × 10 ft area of pea gravel, 3 inches deep: 200 ft² × 0.25 ft = 50 ft³, or 1.85 cubic yards. At 1,600 kg/m³ that weighs about 2.5 US tons — 2.75 tons with 10% extra.
Worked example (UK)
A 6 × 3 m path at 50 mm deep: 18 m² × 0.05 m = 0.9 m³. At 1,600 kg/m³ that is 1.44 tonnes — 1.58 tonnes with 10% extra, or 2 bulk bags of about 850 kg.
Typical material densities
| Material | kg/m³ | US tons per yd³ |
|---|---|---|
| Pea gravel / shingle | 1,600 | 1.35 |
| Crushed stone / gravel (¾″ / 20 mm) | 1,600 | 1.35 |
| Road base / crusher run / MOT Type 1 | 2,100 | 1.77 |
| Sand (dry) | 1,600 | 1.35 |
| River rock / cobbles | 1,500 | 1.26 |
| Slate chippings | 1,450 | 1.22 |
| Topsoil | 1,300 | 1.10 |
These are typical loose densities. Wet material is heavier, and grading varies between quarries, so treat the weight as a close estimate.
Recommended depths
| Project | US depth | UK depth |
|---|---|---|
| Decorative gravel on membrane | 2 in | 40–50 mm |
| Gravel path (top layer) | 2–3 in | 50–75 mm |
| Driveway top layer | 2–3 in | 40–75 mm |
| Path or patio sub-base | 4 in | 100 mm |
| Driveway sub-base | 4–6 in+ | 150 mm+ |
Pouring concrete on top? The concrete calculator works out the slab itself.
Frequently asked questions
How much does a cubic yard of gravel weigh?
About 2,700 lb (1.35 US tons) for typical gravel at 1,600 kg/m³. Pea gravel and crushed stone are close to this; compacted road base is heavier and river rock slightly lighter. Your supplier can tell you the exact density of their material.
How much area does a ton of gravel cover?
One US ton of gravel is about 20 ft³, which covers roughly 120 ft² at 2 inches deep or 80 ft² at 3 inches. In the UK, a bulk bag of about 850 kg covers around 10.5 m² at 50 mm deep.
What is the difference between a ton and a tonne?
A US (short) ton is 2,000 lb or 907 kg. A metric tonne, used by UK merchants, is 1,000 kg or about 2,205 lb. The calculator gives US tons in US mode and tonnes in UK mode.
How deep should a gravel driveway be?
A typical gravel driveway has 4–6 inches (100–150 mm) of compacted base such as crusher run or MOT Type 1, topped with 2–3 inches (40–75 mm) of decorative gravel. On soft ground, a geotextile membrane under the base helps stop it sinking.
Should I order extra for compaction?
Yes. Sub-base materials like crusher run and MOT Type 1 compact by roughly 10–20% when rolled or plate-compacted, so order that much extra. For loose decorative gravel, 5–10% is usually enough to cover uneven ground.