How the Gravel Converter Works
The Gravel Converter divides gravel mass by gravel bulk density for the stone size. The default 1.68 kg/L fits loose crushed gravel.
Pick the gravel size
Pea gravel, 20 mm crushed stone, river rock and road base pack differently.
Enter the density
Use the table value for your gravel.
Enter the mass
Type the weight in kilograms (tonnes × 1,000).
Read the volume
Divide liters by 1,000 for m³, then by area for depth.
Gravel Converter Formula
The gravel formula is V = m ÷ ρgravel. Coverage depth equals volume ÷ area.
- ρgravel
- Gravel bulk density, kg/L (t/m³)
Worked Examples
- 1 t of 20 mm crushed gravel: 1 ÷ 1.68 = 0.595 m³.
- Driveway: 50 m² × 0.075 m × 1.68 = 6.30 t of gravel.
- Pea gravel bag: 20 kg ÷ 1.55 = 12.9 L.
Gravel Converter Conversion Table
1 tonne of loose crushed gravel covers about 11.9 m² at 50 mm (2 in) depth. The table lists 6 gravel types with coverage per tonne.
| Gravel Type | Density (kg/L) | m³ per Tonne | yd³ per Short Ton | Coverage at 50 mm (m²/t) | Coverage at 2 in (ft²/short ton) |
|---|---|---|---|---|---|
| Pea gravel (10 mm) | 1.55 | 0.645 | 0.766 | 12.9 | 124 |
| River rock (20–40 mm) | 1.60 | 0.625 | 0.742 | 12.5 | 120 |
| Crushed stone (20 mm) | 1.68 | 0.595 | 0.706 | 11.9 | 114 |
| Crushed stone (40 mm) | 1.62 | 0.617 | 0.732 | 12.3 | 119 |
| Road base / MOT Type 1 | 2.10 | 0.476 | 0.565 | 9.5 | 92 |
| Decorative slate chips | 1.40 | 0.714 | 0.848 | 14.3 | 137 |
What is a Gravel Converter?
A Gravel Converter is a calculator that converts gravel weight into volume and coverage using bulk density for the stone size.
Gravel is rock in pieces from 2 mm to 64 mm. Crushed stone has sharp faces that lock together; river rock has round faces that roll and leave more voids.
Graded road base mixes fines with larger stones. The fines fill gaps, so road base reaches 2.1 kg/L or more after compaction.
What are the Uses of a Gravel Converter?
There are 4 main uses of a Gravel Converter.
Driveways and paths
Homeowners convert area and depth into tonnes to order.
Drainage
Contractors size French drains and soakaways.
Landscaping
Designers convert bag counts into bed coverage.
Truck loading
Quarries check loads against axle weight limits.