How to use this calculator
- Measure slab length, width, and thickness.
- Choose bagged concrete or ready-mix.
- Enter the package yield or ready-mix price actually offered by your supplier.
The calculation formula
Volume = length × width × thickness (all converted into consistent units). 1 yd³ = 27 ft³; 1 ft³ = 0.028316846592 m³. Bags = ceil(purchase volume ÷ bag yield).
Worked example
A 10 × 10 ft slab 4 in thick uses about 33.33 ft³, or 1.235 yd³, before waste. With 10% waste and 0.6 ft³ per bag, allow 62 bags.
Assumptions and limitations
- This is volume math, not a structural or building-code recommendation.
- Thickness, reinforcement, mixes, foundations and loads require qualified professional review.
Actual project costs may be affected by supplier rates, material grade, labor market, location, disposal, site condition, access, permits, taxes, and schedule. All entered prices are yours to revise. See our methodology and disclaimer.
Frequently asked questions
How many feet are in a cubic yard?
One cubic yard equals 27 cubic feet.
Does the result include truck delivery?
No. Add supplier delivery charges independently; the displayed concrete cost is material only.