Gravel is sold by weight but measured by volume, and it compacts once you spread it. Get either wrong and you're a load short with a half-finished driveway. This does both, and tells you what to ask the yard for.
For driveways, paths, drainage and sub-base. Enter the area and depth, get the tonnage to order — with compaction already allowed for.
Works in metric and US imperial — you choose at the start and can switch at any time. Every figure this calculator uses is published with its source, and the result comes with a printable order sheet. No account, no email, and nothing you type leaves your browser.
Related: Concrete calculator · Asphalt calculator · Fence calculator
All calculators · How to use them · The standards behind our figures
Area × finished depth gives the volume you will see; the compaction allowance puts back the depth that disappears under the plate compactor; the density of the stone you choose converts it to the tonnes or tons the yard sells. Every density figure this site uses is published with its source — and if your yard quotes a different one, use theirs, because they weighed the actual stone.
The single most common way to end up one load short is ordering to the finished depth without allowing for compaction. Spread and plated, general aggregate loses roughly a tenth of its depth; road base loses about a quarter. The calculator allows for this — its allowance is compaction, not waste — so give it the depth you want to end up with, not the depth you plan to tip.
Check where the load can go. A tipper needs headroom to raise its body and firm ground under the wheels, and a load dumped in the wrong spot has to be barrowed twice. If the stockpile has been rained on all week, ask about moisture — you are paying by weight.
Measure the area, decide the finished depth, and add compaction — spread and plate-compacted, loose aggregate loses roughly a tenth of its depth, and road base compacts hardest of all, losing about a quarter. The calculator works from the finished depth you want and the density of the material you pick, and answers in tonnes or tons — the unit yards actually sell in.
No. UK Builders Merchants Federation guidance with Trading Standards is that bulk bags are filled to around 900 kg and marked with a minimum of 850 kg — and in practice many contain closer to 800 kg. Order by the tonne and count bags accordingly, or you will be short by roughly one bag in five.
Order the last load short, not long. Unlike concrete, gravel can be topped up next week with no visible join — so if you are between load sizes, take the smaller one.
Yes, and it matters because yards sell by weight: a wet load delivers less stone for the same tonnage. It is not a scam, it is water — but it is worth asking whether the stockpile is under cover.