Bags concrete calculator
What you need
4.94 cu yd
- Cubic feet
- 133.33 cu ft
- Cubic metres
- 3.776 m³
- Order this much
- 5.43 cu yd
- 80 lb bags
- 245
- 60 lb bags
- 326
- Weight
- 18,670 lb
- Truckloads
- 1
- Cost
- $850 to $1,150
Common sizes
| Size | Cubic yards | 80 lb bags |
|---|---|---|
| 4×4 | 0.20 | 10 |
| 6×6 | 0.44 | 23 |
| 8×8 | 0.79 | 40 |
| 8×10 | 0.99 | 49 |
| 10×10 | 1.23 | 62 |
| 10×12 | 1.48 | 74 |
How this is worked out
volume in cubic feet = width in feet × length in feet × thickness in inches ÷ 12
cubic yards = cubic feet ÷ 27
bags = cubic feet with waste ÷ what one bag yields, rounded up
At the dimensions above that is 133.33 cubic feet, which is 4.94 cubic yards.
What each bag size yields
| Bag size | cu ft | cu yd |
|---|---|---|
| 40 lb | 0.300 | 90 |
| 50 lb | 0.375 | 72 |
| 60 lb | 0.450 | 60 |
| 80 lb | 0.600 | 45 |
| 90 lb | 0.675 | 40 |
Questions
How much concrete do I need for a 20 × 20 ft slab 4 in thick?
4.94 cubic yards, which is 133.33 cubic feet before any waste allowance.
How many bags of concrete is that?
245 eighty-pound bags, or 326 sixty-pound bags, with 10% waste allowed for.
How much does that much concrete cost?
About $850 to $1,150 at $184 per cubic yard delivered. Prices vary by region, so enter a quote of your own to replace the default.
What does that much concrete weigh?
About 18,670 pounds, at 140 pounds per cubic foot.
This site works out quantities. It does not tell you what thickness, reinforcement or sub-base your job needs — those depend on local code and on the load.
Other calculators
Where these numbers come from
Bag yields: QUIKRETE Concrete Mix data sheet No. 1101. Price basis: Concrete Financial Insights weighted average selling price for 2025, escalated with U.S. Bureau of Labor Statistics PPI series PCU327320327320 (2026-06). Prices vary by region — enter your own quote above.