Square feet to cubic yards
Not a unit conversion. An area becomes a volume only when you add a depth.
Material estimate
Enter a figure and a depth — the conversion needs both.
You need to buy
Use this figure
Worth knowing
What this assumes
This is not a conversion
A square foot measures area. A cubic yard measures volume. There is no factor between them, because one has a dimension the other does not — and no amount of arithmetic supplies a depth that was never measured.
Five hundred square feet is 3.09 cubic yards at two inches deep and 18.52 cubic yards at twelve. A factor of six, from the one number every other converter quietly picks for you.
Cubic yards by area and depth
| Area | 2 in | 3 in | 4 in | 6 in | 12 in |
|---|---|---|---|---|---|
| 100 ft² | 0.62 | 0.93 | 1.23 | 1.85 | 3.7 |
| 200 ft² | 1.23 | 1.85 | 2.47 | 3.7 | 7.41 |
| 400 ft² | 2.47 | 3.7 | 4.94 | 7.41 | 14.81 |
| 1,000 ft² | 6.17 | 9.26 | 12.35 | 18.52 | 37.04 |
The depth is doing all the work. Two inches suits decorative cover, four to six a compacted base, twelve imported soil — and the material decides, not the arithmetic.
The formula, and the two places it goes wrong
Cubic yards = square feet × (depth in inches ÷ 12) ÷ 27. Missing the first division leaves the depth in inches against a length in feet, and the answer comes out twelve times too large. Using 9 instead of 27 confuses the square yard with the cubic yard, and the answer comes out three times too large. Both errors are common and both go the same way — too much material.
Then check what the material wants
The volume you have to fill is not always the volume you have to buy. Gravel is ordered loose and laid compacted, so the gravel calculator adds the quarry's compaction factor. Soil settles, so the soil and topsoil calculator carries an allowance for it. For the geometry alone the cubic yard calculator handles circles and repeated areas, and to turn the result into a weight the cubic yards to tons calculator publishes the densities with their sources.
Common questions
How do I convert square feet to cubic yards?
You cannot, not on their own. A square foot is an area and a cubic yard is a volume, so the conversion is missing a dimension — the depth. Once you have one it is straightforward: multiply the area by the depth in inches, divide by 12 to get cubic feet, then divide by 27. Five hundred square feet is 3.09 cubic yards at 2 inches deep and 18.52 at 12.
Why do other converters give an answer without asking for a depth?
Because they have assumed one, and generally without saying so. There is no defensible default: the same area at 2 inches and at 12 inches differs by a factor of six, and a page that picks one silently is not converting anything, it is guessing on your behalf. The depth field on this page is the entire point of it.
What depth should I use?
It follows the material and the job, not the arithmetic. Two inches for decorative gravel or bark over fabric, three for a path people walk on, four to six for a compacted base, twelve or more for imported soil in a bed, four for a residential concrete slab. The material pages on this site each carry the depths that suit them, along with the compaction and settling allowances a bare conversion has none of.
What is the formula?
Cubic yards = square feet × (depth in inches ÷ 12) ÷ 27. The two divisions are the parts that go wrong: dividing the depth by 12 turns inches into feet, and dividing by 27 turns cubic feet into cubic yards. Miss the first and the answer is twelve times too big; use 9 instead of 27 and it is three times too big.
Why 27 and not 9?
Because 9 is the square yard and 27 is the cubic yard. A yard is three feet; 3 × 3 = 9 for an area and 3 × 3 × 3 = 27 for a volume. Substituting one for the other is the commonest error in this whole family of calculations, and it always errs in the same direction — three times too much material.
Does the answer tell me what to order?
Nearly. It gives you the volume you have to fill, which is not always the volume you have to buy — gravel is ordered loose and laid compacted, soil settles over its first season, and both mean ordering more than the hole measures. The material calculators carry those allowances; this page does the geometry.