Volume is where people go wrong, because depth is usually in inches or millimetres while everything else is in feet or metres. This handles the conversion, adds up as many sections as you need, and tells you what it means in loads.
Enter each section — length, width and depth. Add sections for anything that is not one neat box.
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.
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It is three feet in each of three directions, so 3 × 3 × 3. The instinct to divide by three is where most cubic-yard errors start, and they are large errors rather than small ones — a factor of nine. The same trap catches square yards, which are nine square feet rather than three.
Length and width get measured in feet or metres while depth is almost always in inches or millimetres, because that is how people actually work. 100 mm is 0.1 m; 4 inches is a third of a foot. Mixing the two without converting is the second most common error on this page, and it is why the calculator asks for them in separate units rather than pretending everything is in one.
Three cases worth knowing. Sub-base and fill lose roughly a fifth to a quarter of their volume under a compactor, so the amount to order is bigger than the hole. Excavated soil swells about 25%, so a hole produces noticeably more spoil than its own volume — which matters when you are booking a skip. And concrete cannot be topped up: for a poured slab, order a little over and have somewhere to put the surplus, because a cold joint from a short load is a permanent defect. Split irregular excavations into sections rather than averaging a depth that steps.
27. A yard is three feet, and a cubic yard is three feet in each of three directions, so 3 times 3 times 3. Dividing by three instead of 27 is the most common error in volume work.
Convert the depth to feet first — 4 inches is a third of a foot — then multiply length by width by depth in feet, and divide by 27. This calculator handles the unit mixing for you, because measuring length in feet and depth in inches is how the work is actually done.
Not usually. Sub-base and fill lose roughly a fifth to a quarter of their volume under compaction, so you order more than the void. Going the other way, excavated soil swells about 25%, so the spoil is bulkier than the hole it came from.
Split it into sections and add them. A trench that changes depth is two sections rather than one averaged one — averaging is fine for a gentle slope and wrong for a step.