Aggregate tonnage calculator
Tonnes of gravel, sand or MOT Type 1 from area and depth. Set the material — density changes the tonnage at the same volume.
The area
Area to be covered.
50mm for a top-dress; 100mm+ for a sub-base.
Tonnes required
— 1.00m³ at this depth.
Illustrative only. Based on standard bulk densities — actual weight varies by moisture content and exact grading. Confirm with your supplier for a large order.
Aggregate is priced and delivered by the tonne, not the bag, so getting the order right matters more than it does for smaller materials. Under-order and the lorry's back for a top-up you're paying a second delivery charge for. Over-order and you're paying to have a part-load taken away, or it sits in a pile on the drive for months.
Why material changes the tonnage
The same volume of different aggregates weighs different amounts — MOT Type 1 sub-base is denser than loose gravel or sand, because it's a graded mix that compacts tightly with very little air gap between particles. That's exactly why it's specified under driveways and paths: density is what gives it load-bearing strength. Loose decorative gravel and building sand sit lighter and looser by comparison.
Depth depends on the job
A thin top-dress or decorative gravel layer might only need 50mm. A proper sub-base under a driveway or patio typically runs 100mm or more, sometimes considerably deeper depending on the ground and what's going on top. Check the spec for the specific job rather than assuming one depth fits every use.
A worked example
20m² at 50mm deep in gravel comes to 1m³ and 1.5 tonnes — roughly two bulk bags. Swap to MOT Type 1 at the same area and depth and the weight jumps to 2 tonnes, because the material itself is denser, not because there's more of it.
Where this falls short
Bulk density varies with moisture and the exact grading a supplier stocks, so treat this as a planning figure rather than an exact order quantity. For a large or expensive delivery, confirm the tonnage with the supplier directly — most will size the load for you once they know the area and depth.
Delivery and access
Anything past a bulk bag or two usually comes loose, tipped from the back of a lorry — which means checking access before you order, not after it's blocking the drive. Narrow lanes, low bridges and tight turns can rule out a full artic delivery, and some suppliers charge extra for a wait-and-load service if there's nowhere sensible to tip a full load.
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