Cubic yards = square feet × depth in inches ÷ 12 ÷ 27, or square feet × depth ÷ 324: 500 sq ft filled 4 in deep is 500 × 4 ÷ 324 = 6.17 cubic yards. Square feet alone cannot be converted to cubic yards, because volume needs a depth.
How to convert square feet to cubic yards
Cubic yards = area (sq ft) × depth (in) ÷ 12 ÷ 27 = area × depth ÷ 324
Step by step for 500 sq ft at 4 in: the depth is 4 ÷ 12 = 0.3333 ft, the volume is 500 × 0.3333 = 166.7 cubic feet, and 166.7 ÷ 27 cubic feet per cubic yard is 6.17 cubic yards. With 10% extra for uneven ground and spillage, order 6.79 cubic yards. The calculator shows the whole chain and rounds the purchase up to the next quarter yard.
No area yet? Switch to length by width and enter feet and inches. Metric works with square meters and centimeters, and the answer is also given in cubic meters (1 cubic yard is 0.7646 m³, NIST Handbook 44).
Square feet to cubic yards of concrete
A slab is normally 4 in thick. 400 sq ft (20 ft by 20 ft) at 4 in is 400 × 4 ÷ 324 = 4.94 cubic yards. A 12 ft by 40 ft driveway pad, 480 sq ft, is 5.93 cubic yards at 4 in. Concrete is delivered by the cubic yard and usually ordered with a margin, and the concrete slab calculator adds rebar and bags. At 4,050 lb per cubic yard, the 500 sq ft slab in the example weighs 25,000 lb, or 12.5 tons.
Square feet to cubic yards of gravel, sand and topsoil
Gravel base under a pad, 300 sq ft at 4 in, is 300 × 4 ÷ 324 = 3.70 cubic yards. Topsoil for a lawn, 1,000 sq ft at 3 in, is 9.26 cubic yards. Sand under pavers, 100 sq ft at 2 in, is 0.62 cubic yards. Suppliers often sell these by the ton, so the calculator shows the weight of the material you pick: 6.17 cubic yards of dry topsoil at 2,300 lb per yard is 7.10 tons. Convert either way with the cubic yards to tons calculator.
Square feet to cubic yards of mulch
A mulch bed of 200 sq ft at 3 in deep is 200 × 3 ÷ 324 = 1.85 cubic yards. Mulch is light, about 473 lb per yard when fresh, so the weight is rarely the limit; the volume of your truck or trailer is.
Area one cubic yard covers
| Depth | Sq ft per cubic yard | Cubic yards per 1,000 sq ft |
|---|---|---|
| 1 in | 324 | 3.09 |
| 2 in | 162 | 6.17 |
| 3 in | 108 | 9.26 |
| 4 in | 81 | 12.35 |
| 6 in | 54 | 18.52 |
| 8 in | 40.5 | 24.69 |
| 12 in | 27 | 37.04 |
The Texas A&M AgriLife Extension guide for compost, soil and mulch uses the same relation, length × width × depth in inches ÷ 12 ÷ 27.
Depth is the missing input
Choose the job first (slab, gravel base, topsoil, mulch, sand) and the depth chip fills in the usual figure: 4, 4, 3, 3 and 2 in. Change it if your plan differs. Compacted material needs more than the loose calculation: a base that is compacted from 6 in loose to 4 in needs about half again as much delivered.
What to work out next
The volume calculators for other shapes are the cubic yard calculator and the cubic feet calculator. Measure an odd-shaped area first with the square footage calculator, and if you are digging out instead of filling, plan the haul with the dumpster size calculator. The full set is in measuring and planning calculators.