TidyToolsHow much gravel or aggregate do I need?
It's a two-step job: first the volume, then the weight. Volume is simply area × depth — but the depth is usually in centimetres or inches while the area is in metres or feet, so it needs converting. This calculator handles that. Once it knows the volume, it converts to weight using the material's density, because gravel, sand, topsoil, and mulch all weigh very different amounts for the same volume — and suppliers sell most of these by weight (the tonne or ton), or in bulk bags.
Pick your material, enter the length, width, and depth of the area you're covering, and you'll get the volume plus the weight to order. As a rule of thumb, gravel for a path or driveway is laid about 5 cm (2 in) deep for a top-up, or 10 cm+ for a fresh sub-base.
A worked example
A 5 m × 3 m area (15 m²) covered with gravel 5 cm deep is 0.75 m³. Gravel weighs roughly 1.5 tonnes per cubic metre, so you'd order about 1.1 tonnes — usually one bulk bag plus a bit, so round up to be safe.
Tips
- Densities vary — wet or compacted material weighs more. Treat the result as a close estimate and round up.
- Bulk bags hold roughly 0.5–0.8 tonnes depending on the supplier; check before ordering.
- Deeper for driveways — a load-bearing sub-base needs more depth than a decorative top layer.
- Order a little extra for settling and topping up.
Frequently asked questions
How do I work out gravel weight from volume?
Multiply the volume (area × depth) by the material's density. Gravel is about 1.5 tonnes per cubic metre; sand, topsoil and mulch differ, which is why you pick the material here.
How deep should gravel be?
About 5 cm (2 in) for a decorative top-up, and 10 cm or more for a new sub-base or driveway that needs to bear weight.
How much does a bulk bag cover?
A bulk bag is roughly 0.5–0.8 tonnes. At 5 cm deep, that typically covers somewhere around 6–10 m² — check your supplier's exact bag weight.