How to calculate cubic yards
Almost every bulk material — concrete, gravel, mulch, topsoil — is ordered in cubic yards. Here's the formula, the unit traps and worked examples you can copy.
On this page
The formula
A cubic yard is a cube 3 feet on each side: 3 × 3 × 3 = 27 cubic feet. So:
The only trap is units. Depth is usually measured in inches, so convert it to feet by dividing by 12 before you multiply.
| Depth | In feet |
|---|---|
| 1 in | 0.083 ft |
| 2 in | 0.167 ft |
| 3 in | 0.25 ft |
| 4 in | 0.333 ft |
| 6 in | 0.5 ft |
| 12 in | 1 ft |
A shortcut for area × inches
If you already know the area in square feet and the depth in inches:
That's because 12 × 27 = 324. It also means one cubic yard covers 324 square feet at 1 inch deep, 162 at 2 inches, 108 at 3 inches and 81 at 4 inches.
Worked examples
A 10 × 12 ft patio slab, 4 inches thick
- 10 × 12 × 0.333 = 40 ft³
- 40 ÷ 27 = 1.48 cubic yards
A flower bed of 150 sq ft, 3 inches of mulch
- 150 × 3 ÷ 324 = 1.39 cubic yards
A round fire pit area 14 ft across, 3 inches of pea gravel
- Area: π × 7² = 153.9 sq ft
- 153.9 × 3 ÷ 324 = 1.43 cubic yards
Odd shapes
Split the area into rectangles, triangles and circles, work out each area and add them up — then multiply by the depth. The square footage calculator adds shapes for you, and how to measure an irregular area covers curves.
Metric
From cubic yards to what you buy
- Concrete: ready-mix is ordered in cubic yards; bags are counted by yield (45 bags of 80 lb per yard) — use the concrete calculator.
- Gravel and sand: often sold by the ton — multiply yards by the density (about 1.4 for crushed stone). See cubic yards to tons.
- Mulch and soil in bags: divide cubic feet by the bag size (a yard is 13.5 bags of 2 cu ft).
- Always add a margin — 5 to 10% for waste, settling and uneven ground.
Frequently asked questions
How many cubic feet are in a cubic yard?
27.
How many square feet does a cubic yard cover?
324 ÷ depth in inches: 108 sq ft at 3 inches, 81 sq ft at 4 inches.
How do I convert cubic feet to cubic yards?
Divide by 27. For example, 54 cubic feet is 2 cubic yards.