Concrete Slab Calculator
The short answer for a 10×10 ft slab, 4 inches thick: 62 bags of 80 lb mix (1.23 cubic yards). Enter your slab below for your number.
Materials list
| Item | Quantity |
|---|---|
| Concrete mix — 80 lb bags (0.60 cu ft yield per bag) | 62 bags |
| Ready-mix equivalent (before wastage) | 1.23 cubic yards |
How it works
Slab volume is length times width times thickness, converted to cubic feet and then to cubic yards (27 cu ft per yard). Bags are the volume plus your wastage allowance, divided by the yield of your bag size and rounded up. Yields are the manufacturer's own figures: an 80 lb bag of QUIKRETE Concrete Mix yields 0.60 cu ft, a 60 lb bag 0.45, a 50 lb bag 0.375 and a 40 lb bag 0.30 — cross-checked against the SAKRETE High Strength data sheet, which agrees exactly at 40, 60 and 80 lb.
Sources: QUIKRETE Concrete Mix No. 1101 Data Sheet (quikrete.com, rev. Oct 2022) and QUIKRETE 5000 No. 1007 Data Sheet (rev. Nov 2022); cross-checked against SAKRETE High Strength Concrete Mix TDS. Full evidence: research-data/mulch-paint-concrete.md Retrieved 2026-10-24.
Questions
How many bags of concrete for a 10×10 slab, 4 inches thick?
A 10×10 ft slab at 4 in is 33.33 cu ft (1.23 cubic yards). With 10% wastage that is 62 bags of 80 lb mix — an 80 lb bag yields 0.60 cu ft (QUIKRETE Concrete Mix No. 1101 data sheet).
How many 80 lb bags of concrete are in a cubic yard?
45 bags. That is arithmetic from QUIKRETE's stated yield (27 cu ft per cubic yard ÷ 0.60 cu ft per bag); no manufacturer data sheet states a bags-per-yard figure directly.
How thick should a concrete slab be?
QUIKRETE 5000's data sheet covers applications at a minimum thickness of 2 in, such as slabs, footings, steps and patios. Four inches is the usual planning thickness for a patio or walkway slab, which is this calculator's worked example.