Concrete Calculator
Enter your project's dimensions to find out how many cubic yards of concrete to order. Use the concrete bag calculator to convert yards to bag counts.
Results
- Cubic yards
- 0.93 yd³
- Cubic feet
- 25.0 ft³
- Weight
- 1.88 tons
- Bags
- 42 × 80 lb bag
Assumed density: 4050 lb/yd³ (Concrete (wet mix))
How it works
Enter the pour's length and width in feet, and the thickness in inches.
The calculator converts total cubic inches to cubic feet, then divides by 27 to get cubic yards — the standard unit for ready-mix orders.
Always add 5–10% to your order to account for spillage, uneven sub-base, and finishing waste. Round up to the nearest 0.25 yards.
Reference chart
Concrete coverage by thickness (1 cubic yard)
| Thickness (in) | 1 yd³ covers (sq ft) |
|---|---|
| 3 | 108 |
| 4 | 81 |
| 5 | 65 |
| 6 | 54 |
| 8 | 41 |
Frequently asked questions
How many cubic yards of concrete do I need for a 20×30 ft slab, 4 inches thick?
20 × 30 × (4/12) = 200 cu ft ÷ 27 ≈ 7.4 yd³. Order 8 yards to allow for a small buffer.
How much extra concrete should I add to my order?
Add 5–10% for residential pours. A 7 yd³ base order becomes 7.35–7.7 yd³; round up to the nearest 0.25 or 0.5 yard your supplier offers.
How do I convert cubic yards of concrete to bags?
One cubic yard equals 27 cu ft. An 80 lb bag yields 0.60 cu ft, so 1 yd³ needs about 45 × 80 lb bags. Use the concrete bag calculator for an exact count.