How Much Concrete for a 10 × 20 Slab?
A 10 × 20 ft slab is 200 sq ft. It needs 2.72 cubic yards of concrete at 4 inches thick or 4.07 yd³ at 6 inches, including 10% extra.
| Order | 4 in thick | 6 in thick |
|---|---|---|
| Cubic yards | 2.72 | 4.07 |
| 80-lb bags | 123 | 184 |
| 60-lb bags | 163 | 245 |
| 50-lb bags | 196 | 294 |
| 40-lb bags | 245 | 367 |
| Cubic meters | 2.08 | 3.11 |
Concrete needed
2.72 cubic yards
73.3 ft³ · 2.08 m³ · includes 10% extra
You need about 2.72 cubic yards of concrete, or 123 bags of 80 lb mix.
Bags of premix
- 24540 lb bags
- 19650 lb bags
- 16360 lb bags
- 12380 lb bags
- —20 kg bags
- —25 kg bags
- Before extra2.47 yd³ (66.7 ft³)
- Weight of bags9,840 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.
At 2.72 yd³ that is 123 × 80 lb bags (9,840 lb) to mix. Most people order ready-mix at this size; ask suppliers for their minimum load and any short-load fee.
Estimate only, not a quote or engineering advice. Disclaimer
A 10 × 20 ft slab is a long patio, a single-car parking pad or a base for a 10 × 20 carport or storage building.
10 × 20 slab at other thicknesses
| Thickness | yd³ exact | yd³ +10% | 80-lb bags | 60-lb bags |
|---|---|---|---|---|
| 3.5 in | 2.16 | 2.38 | 107 | 143 |
| 4 in | 2.47 | 2.72 | 123 | 163 |
| 5 in | 3.09 | 3.40 | 153 | 204 |
| 6 in | 3.70 | 4.07 | 184 | 245 |
| 8 in | 4.94 | 5.43 | 245 | 326 |
How it's worked out
For bags, the 73.3 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 9,300 lb, using the 140 lb/ft³ unit weight QUIKRETE lists for its Concrete Mix.
Bags or a truck?
At 2.72 yd³ you would need 123 × 80-lb bags (about 9,840 lb) and a long session with a mixer and helpers. Most people order ready-mix at this size: call suppliers with the yardage and ask for their minimum load and any short-load fee.
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 10x20 slab?
2.47 cubic yards at 4 inches thick and 3.70 yd³ at 6 inches, before waste. With 10% extra, order 2.72 or 4.07 yd³.
How many bags of concrete for a 10x20 slab?
At 4 inches with 10% extra: 123 bags of 80-lb mix, 163 of 60 lb, 196 of 50 lb or 245 of 40 lb. At 6 inches: 184 bags of 80 lb or 245 of 60 lb.
How many cubic feet of concrete for a 10x20 slab?
66.7 ft³ at 4 inches (200 sq ft × 4 ÷ 12) and 100.0 ft³ at 6 inches, before waste.
How thick should a 10x20 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)