How Much Gravel for a Driveway?
Quick Answer
You need approximately 1.28 tonnes (0.75m³) of gravel
Based on: 5m x 3m driveway, 50mm depth of 20mm decorative gravel, bulk density ~1.7 tonnes/m³
How We Calculated This
Gravel quantity is calculated as a volume, then converted to weight using the bulk density of the material:
- Area: 5m x 3m = 15m²
- Depth: 50mm = 0.05m
- Volume: 15 x 0.05 = 0.75m³
- Weight: 0.75 x 1.7 = 1.275 tonnes, say 1.28 tonnes
Why 50mm Depth?
For a decorative gravel driveway surface (the top layer), 50mm is the standard minimum depth. This gives enough coverage to hide the sub-base and look consistent when walked or driven on. For pedestrian paths, 25–30mm is sufficient.
Bulk Density of Common Gravels
- 20mm decorative gravel: ~1.7 tonnes/m³
- 10mm pea gravel: ~1.6 tonnes/m³
- 20mm golden gravel: ~1.7 tonnes/m³
- Slate chippings: ~1.5 tonnes/m³
- Type 1 MOT (sub-base): ~1.8 tonnes/m³
Don’t Forget the Sub-Base
A gravel driveway for vehicles must have a compacted sub-base to prevent sinking and rutting. The typical build-up is:
- Geotextile membrane on the ground to prevent weed growth
- Type 1 MOT sub-base: 100–150mm compacted depth
- Decorative gravel: 50mm top layer
For the sub-base on a 5m x 3m driveway at 100mm depth, you need: 15 x 0.1 x 1.8 = 2.7 tonnes of Type 1.
Buying Guide
- Bulk bags (850kg–1 tonne): Most cost-effective for driveways. You would need 2 bulk bags.
- Loose/tipped: Cheapest per tonne for larger quantities. Minimum order is typically 3–5 tonnes.
- 25kg bags: Convenient but expensive — you would need about 52 bags.
Tips
Use a gravel grid/honeycomb stabilisation system if the driveway will take regular vehicle traffic — this prevents gravel migration and reduces the depth of gravel needed. An edging of treated timber, metal, or brick keeps the gravel contained.