How many yards of dirt do I need?

How does the arithmetic work?

A cubic yard is 27 cubic feet: a block 3 feet by 3 feet by 3 feet. To work out what you need, multiply the length in feet by the width in feet by the depth in feet, then divide by 27. That is the whole calculation, and everything else on this page is about the allowance you add to the answer.

Depth is almost always given in inches, so divide the inches by 12 first. 4 inches is 0.333 feet. 6 inches is 0.5 feet. A 20 foot by 30 foot area at 4 inches deep works out at 20 times 30 times 0.333, which is 200 cubic feet, or about 7.4 cubic yards.

For weight, 1 cubic yard of aggregate, sand or dirt runs about 1.5 tons as a general guide. That is the figure we publish on our own tools page. Wet clay is heavier than dry topsoil, so treat it as a planning number rather than a scale reading, and use it for working out truck loads rather than for a weight ticket.

Why do I have to allow for settlement?

Loose material off a truck occupies more space than the same material once it has been spread, watered and walked on. How much more depends on what it is and how it is placed, but it is never zero. This is the single most common reason a job comes up short on the last load.

For topsoil going down to a finish level you care about, add about 10 percent and rake it slightly proud so it settles into the level rather than below it. For clay fill being placed and settled, 10 to 20 percent. For select fill being compacted in lifts to a specification, budget 20 to 25 percent, because the compacted volume will be meaningfully less than the loose volume you bought. That is the compaction doing its job.

Running short is worse than running over. A second trip to top up a job is a full trucking charge on a small quantity, which is the most expensive dirt you will ever buy. Trucking is roughly 90 percent of the cost of a load, and that cost does not scale down when the quantity does.

How do I handle awkward shapes?

Pools and ponds are what people get wrong most often. A pool is not a box. It has a shallow end, a deep end and a transition, so estimate it as an average depth across the whole footprint rather than using the shallow-end depth. For a typical residential pool that average often lands near 5 feet, which is a great deal more yardage than the 3 feet people picture. A 16 foot by 32 foot pool at an average 5 feet is about 95 cubic yards.

For circles, the area is pi times the radius squared. A 24 foot diameter circle has a 12 foot radius, so the area is about 452 square feet. At 6 inches deep that is 226 cubic feet, or about 8.4 cubic yards.

For a sloping yard, break it into sections with roughly even depth, work each one out separately and add them up. Measuring the deepest point and applying it across the whole area is the fastest way to over-order by double. If you genuinely cannot work it out, give us the dimensions and what you are doing and we will run it with you on the phone.

Worked examples

4 jobs we get asked to price constantly, with the arithmetic shown so you can check it against your own dimensions rather than taking our word for the answer.

Where do I go from here?

Once you have a number, we need the delivery address to price it, because haul distance is the biggest single variable in what a cubic yard costs. The minimum order is 20 cubic yards. If your figure is close to the minimum, check the whole area you want covered before you call, because most people find a second low spot.

Bags, tons, wheelbarrows and pickups Yards per dump truck