Square feet measure area, cubic yards measure volume, so you need a depth to convert between them. That is exactly the situation when you know the size of a bed, patio or slab and want to order bulk material. A quick rule: one cubic yard covers 324 ft² at an inch deep.
How to use the Square Feet to Cubic Yards Calculator
- Area
- Depth
- Extra allowance
- Price per cubic yard (optional)
- Every result field is editable: type into Volume and Depth plus every other field update to match.
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter the area and the depth of the layer, plus an optional extra allowance. The calculator multiplies area by depth and divides by 27 ft³ per yd³. You can also type the cubic yards you have to find the depth they will cover.
Quick reference: cubic yards per 100 ft²
| Depth | yd³ per 100 ft² |
|---|---|
| 1 in | 0.309 |
| 2 in | 0.617 |
| 3 in | 0.926 |
| 4 in | 1.235 |
| 6 in | 1.852 |
| 8 in | 2.469 |
| 12 in | 3.704 |
Tips for an accurate estimate
- Measure every dimension twice and write the unit next to each number – most estimating errors are unit mix-ups (inches entered as feet).
- Pick the unit in each field’s menu instead of converting by hand; the calculator converts everything to the same base before it multiplies.
- Round up only at the very end. Rounding each dimension first can add several percent to the final quantity.
- Suppliers sell in whole units – bags, boxes, sheets or quarter yards – so always round the final order up, not down.
Common mistakes to avoid
- Mixing square and cubic units: square feet measure area, cubic yards measure volume, and you need a depth to go from one to the other.
- Using nominal lumber sizes where actual sizes matter (a 2×4 is really 1½ × 3½ in).
- Forgetting that 1 yd³ = 27 ft³, not 9 ft³ (9 is for square yards).
Inputs explained
| Field | What to enter |
|---|---|
| Area | Units: ft², m², yd², acre |
| Depth | Units: in, cm, mm, ft, m |
| Extra allowance | In % |
| Price per cubic yard (optional) | Units: /yd³, /m³, /ft³ |
What each result means
- Volume = [Area]×[Depth]×(1 + [Extra allowance]÷100)
- Volume in cubic feet = [Volume]
- Cost = [Volume]×[Price per cubic yard (optional)]
Formula
Cubic yards = area (ft²) × depth (ft) ÷ 27 = area (ft²) × depth (in) ÷ 324Worked example
Inputs — Area: 400 ft²; Depth: 3 in; Extra allowance: 0 %; Price per cubic yard (optional): $0 /yd³.
Results — Volume = 3.704 yd³; Volume in cubic feet = 100 ft³; Cost = $0.00.
Frequently asked questions
How many square feet does a cubic yard cover?
324 ft² ÷ depth in inches – so 108 ft² at 3 in or 81 ft² at 4 in.
How do I convert square feet to cubic yards without depth?
You can't; area and volume are different quantities. Pick the depth you plan to spread.
How many cubic yards for 1,000 ft² at 4 inches?
1,000 × 4 ÷ 324 = 12.35 yd³.
What formula does the Square Feet to Cubic Yards Calculator use?
Cubic yards = area (ft²) × depth (ft) ÷ 27 = area (ft²) × depth (in) ÷ 324.