How this is worked out
Volume is area × depth in metres. Tonnes is volume × density. We default to 1.7 tonnes per m³, the figure Beesley & Fildes say contractors use for estimates (their measured figure for typical gravel is 1.68).
Bulk bags assume about 860kg each, based on 43 bags of 20kg. Some merchants sell lighter “jumbo” bags, so compare the weight printed on the listing with this.
Worked example
A path 12m long and 0.9m wide at 50mm deep: 12 × 0.9 × 0.05 = 0.54 m³. At 1.7 tonnes per m³ that’s 0.92 tonnes. That’s just over one 860kg bulk bag, so order one bulk bag and three or four 20kg bags, or 46 bags of 20kg on their own.
Tips for a gravel path or drive
- Lay a permeable weed membrane first, and use an edging board so the stones stay put.
- Angular stone like 20mm limestone locks together better than round pea shingle, which rolls underfoot.
- For a drive, put the gravel on top of a compacted sub-base. You can work out the sub-base tonnage here too by entering its depth and a density of about 2.1.
Questions people ask
How much gravel do I need for a path?
Multiply the length by the width by the depth. A 10m × 1m path at 50mm deep needs 0.5 m³, which is about 0.85 tonnes, or one bulk bag.
How deep should gravel be?
Around 40 to 50mm for a path or garden area over a weed membrane. Driveways usually go deeper, on top of a compacted sub-base, so the stones don’t rut.
How much does a bulk bag of gravel cover?
Beesley & Fildes put a bulk bag at about 43 bags of 20kg, around 860kg. At 50mm deep that covers roughly 10 m². Bags from other suppliers can be lighter, so check the weight.
Is gravel heavier than soil?
Gravel is about 1.7 tonnes per m³ by contractors’ reckoning. That’s more than most people expect, so check what your car or trailer can carry.
Sources
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Figures last checked 25 October 2026. Read how we calculate and our disclaimer. Found a mistake? Tell us.