How Much Gravel Do I Need for a Driveway?
Quick answer: As a rule of thumb, 1 tonne of gravel covers about 10–12 square metres at a 50mm depth (or roughly 100 sq ft at 2 inches). For a new driveway you’ll usually lay gravel 50mm deep, so a typical 5m × 4m driveway (20 m²) needs about 2 tonnes of gravel — plus a compacted sub-base underneath. Volume converts to weight using the gravel’s density, which varies by material, so the exact tonnage depends on which gravel you choose.
Gravel is sold by weight, but you measure your driveway by area — and bridging that gap is where most people either over-order and waste money or under-order and stop halfway through the job. A driveway is also more than just the loose gravel on top: it needs a proper base to bear the weight of a car without rutting. This guide walks through the calculation, the depth to actually use, the sub-base you’ll also need, and why the volume-to-tonnes step trips people up. Use the calculator above for your exact figure.
The three numbers you need
Working out gravel comes down to area, depth, and density:
- Area — length × width of the driveway, in square metres (or square feet).
- Depth — how thick the gravel layer will be. For a driveway, 50mm (2in) is standard for the decorative top layer.
- Density — how heavy that gravel is per cubic metre, which converts your volume into tonnes and then into bulk bags.
Area × depth gives you a volume. The density turns that volume into the weight your supplier actually sells. Miss the density step and you can’t order correctly — which is exactly why generic calculators built for one gravel type give the wrong numbers for another.
Coverage rule of thumb
For quick planning, at a 50mm depth, one tonne of typical gravel covers roughly 10–12 m² (about 108–130 sq ft), and one UK bulk bag (around 800–850kg) covers roughly 9–10 m² at the same depth.
So a few common driveway sizes at 50mm:
| Driveway size | Approx. area | Gravel needed (50mm) |
|---|---|---|
| 5m × 3m | 15 m² | ~1.5 tonnes |
| 5m × 4m | 20 m² | ~2 tonnes |
| 6m × 5m | 30 m² | ~3 tonnes |
| 8m × 6m | 48 m² | ~4.5–5 tonnes |
These are top-layer figures only. A proper driveway also needs a sub-base below the gravel — see below — which is a separate quantity to calculate and order.
Why gravel type changes the weight
Not all gravel weighs the same per cubic metre. Angular 20mm gravel, rounded pea shingle, slate chippings, and denser crushed stone all have different densities, so the same volume comes out as different tonnages. A calculator that assumes a single density will be wrong for most materials. Matching the density to your actual material is what makes the tonnage accurate, and it’s the detail worth getting right before a bulk delivery you can’t send back. For a driveway specifically, angular gravel is the right choice because its sharp faces interlock and stay put under tyres, unlike rounded pea shingle which scatters.
Don’t forget the sub-base
A gravel driveway isn’t just gravel. For it to bear the weight of a car without rutting, you need a compacted sub-base — usually MOT Type 1 — beneath the decorative top layer. A common build is:
- 100–150mm of compacted MOT Type 1 sub-base, then
- 50mm of gravel or decorative aggregate on top.
That means you’re ordering two materials in two quantities. Calculate the sub-base at its depth (with MOT Type 1’s higher density), and the gravel at 50mm separately, then order both. Skimping on the sub-base is the most common cause of a driveway that ruts and sinks within a season — the gravel on top is only as good as the base beneath it.
Edging keeps it in place
Loose gravel spreads sideways without a border, migrating onto lawns, into flowerbeds, and off the edge of the drive. Edging — timber, metal, brick, or a concrete kerb — holds the gravel in place, keeps the depth even, and saves you constantly raking it back. It’s a small addition that makes a big difference to how a gravel driveway looks and performs over time.
Common mistakes to avoid
The main mistakes are ordering gravel without a sub-base (which leads to rutting), using rounded pea shingle instead of angular gravel (which scatters under tyres), laying the gravel too deep (over about 50mm of loose gravel ruts), and calculating with a generic density rather than the one for your actual material. One more: forgetting a waste allowance. Add about 5% for spreading and settling so you don’t come up short finishing the drive.
Frequently asked questions
How many tonnes of gravel for a driveway?
For a standard car driveway, budget around 2 tonnes per 20 m² at a 50mm top layer, plus the sub-base beneath. The exact tonnage depends on the gravel type’s density — denser crushed stone weighs more per cubic metre than lighter decorative aggregate.
How deep should gravel be on a driveway?
About 50mm (2in) for the decorative top layer, over a compacted sub-base of 100–150mm. Deeper loose gravel just ruts and scatters under tyres, so the depth belongs in the sub-base, not the surface.
How much does 1 tonne of gravel cover?
Roughly 10–12 m² (108–130 sq ft) at 50mm deep. Lay it deeper and 1 tonne covers proportionally less area; at 30mm it covers more. Denser gravels cover slightly less per tonne than lighter ones.
Is a bulk bag a tonne?
Not always. UK bulk bags typically hold around 800–850kg, not a full 1,000kg tonne, so check your supplier’s stated bag weight before converting tonnes to bags. Heavier aggregates can be closer to a full tonne in the same volume.
What gravel is best for a driveway?
Angular gravel, usually 20mm, because its sharp faces interlock and stay firm under tyres. Rounded pea shingle looks attractive but rolls and scatters under vehicles. Lay it over a compacted MOT Type 1 sub-base for a stable, long-lasting surface.
Do I need a sub-base under a gravel driveway?
Yes. A compacted MOT Type 1 sub-base of 100–150mm bears the weight of vehicles and stops the driveway rutting. Loose gravel laid straight onto soil sinks and ruts within a season. The sub-base is a separate material and quantity from the gravel on top.