How Much Concrete for a 4 × 4 Slab?
A 4 × 4 ft slab is 16 sq ft. It needs 0.22 cubic yards of concrete at 4 inches thick or 0.33 yd³ at 6 inches, including 10% extra.
| Order | 4 in thick | 6 in thick |
|---|---|---|
| Cubic yards | 0.22 | 0.33 |
| 80-lb bags | 10 | 15 |
| 60-lb bags | 14 | 20 |
| 50-lb bags | 16 | 24 |
| 40-lb bags | 20 | 30 |
| Cubic meters | 0.17 | 0.25 |
Concrete needed
5.87 cubic feet
0.217 yd³ · 0.166 m³ · includes 10% extra
You need about 5.87 cubic feet of concrete, or 10 bags of 80 lb mix.
Bags of premix
- 2040 lb bags
- 1650 lb bags
- 1460 lb bags
- 1080 lb bags
- —20 kg bags
- —25 kg bags
- Before extra0.20 yd³ (5.3 ft³)
- Weight of bags800 lb
- Per hole—
- Ready-mix costAdd a price per yd³
- Bagged costAdd a price per bag
One 80 lb bag makes about 0.60 ft³ (manufacturer's published yield). Bags are rounded up.
Bagged mix makes sense at 0.22 yd³. A ready-mix truck for a load this small would usually come with a minimum-order or short-load charge.
Estimate only, not a quote or engineering advice. Disclaimer
A 4 × 4 ft pad is a common base for an AC condenser, a generator, a grill or a trash can corral. It is a small enough pour to mix by hand in a wheelbarrow.
4 × 4 slab at other thicknesses
| Thickness | yd³ exact | yd³ +10% | 80-lb bags | 60-lb bags |
|---|---|---|---|---|
| 3.5 in | 0.17 | 0.19 | 9 | 12 |
| 4 in | 0.20 | 0.22 | 10 | 14 |
| 5 in | 0.25 | 0.27 | 13 | 17 |
| 6 in | 0.30 | 0.33 | 15 | 20 |
| 8 in | 0.40 | 0.43 | 20 | 27 |
How it's worked out
For bags, the 5.9 ft³ (with extra) is divided by each bag's yield: 0.60 ft³ for 80 lb, 0.45 for 60 lb, 0.375 for 50 lb and 0.30 for 40 lb, then rounded up. At 4 inches the slab itself weighs about 700 lb, using the 140 lb/ft³ unit weight QUIKRETE lists for its Concrete Mix.
Bags or a truck?
At 0.22 yd³ (10 × 80-lb bags), bagged mix is the practical choice. A ready-mix truck for a load this small would usually carry a minimum-order or short-load charge.
Don't forget the base: most slabs sit on a compacted layer of gravel, and thicker edges or footings around the perimeter add concrete. Use the footing calculator for a thickened edge.
Frequently asked questions
How many yards of concrete for a 4x4 slab?
0.20 cubic yards at 4 inches thick and 0.30 yd³ at 6 inches, before waste. With 10% extra, order 0.22 or 0.33 yd³.
How many bags of concrete for a 4x4 slab?
At 4 inches with 10% extra: 10 bags of 80-lb mix, 14 of 60 lb, 16 of 50 lb or 20 of 40 lb. At 6 inches: 15 bags of 80 lb or 20 of 60 lb.
How many cubic feet of concrete for a 4x4 slab?
5.3 ft³ at 4 inches (16 sq ft × 4 ÷ 12) and 8.0 ft³ at 6 inches, before waste.
How thick should a 4x4 slab be?
Four inches is usual for patios, walkways and shed pads. Garage floors, driveways and pads for heavy loads are commonly 5 to 6 inches. Follow local code or your plans for anything structural.
Other slab sizes
Related
Sources
- QUIKRETE: Concrete Mix No. 1101 data sheet (Revised Oct 2022; checked Nov 11, 2026)