How much concrete common slabs, pads and footings take: cubic yards for ordering ready-mix, and whole 80, 60 and 40 lb bags of premix. The numbers come from the same math as the concrete calculator, length × width × thickness, with a bag yield of about 0.60 cu ft for an 80 lb bag, 0.45 for 60 lb and 0.30 for 40 lb.
No waste is included. Add 5% to 10% for an uneven base, forms that bow out and spillage, and check the yield printed on your bag, which varies a little by brand and mix.
4" thick slabs
4" thick slabs| Slab (ft) | Cubic yards | 80 lb bags | 60 lb bags | 40 lb bags |
|---|
| 4 × 4 | 0.20 | 9 | 12 | 18 |
|---|
| 4 × 8 | 0.40 | 18 | 24 | 36 |
|---|
| 8 × 8 | 0.79 | 36 | 48 | 72 |
|---|
| 10 × 10 | 1.23 | 56 | 75 | 112 |
|---|
| 10 × 12 | 1.48 | 67 | 89 | 134 |
|---|
| 12 × 12 | 1.78 | 80 | 107 | 160 |
|---|
| 12 × 16 | 2.37 | 107 | 143 | 214 |
|---|
| 12 × 20 | 2.96 | 134 | 178 | 267 |
|---|
| 16 × 16 | 3.16 | 143 | 190 | 285 |
|---|
| 20 × 20 | 4.94 | 223 | 297 | 445 |
|---|
| 24 × 24 | 7.11 | 320 | 427 | 640 |
|---|
5" thick slabs
5" thick slabs| Slab (ft) | Cubic yards | 80 lb bags | 60 lb bags | 40 lb bags |
|---|
| 4 × 4 | 0.25 | 12 | 15 | 23 |
|---|
| 4 × 8 | 0.49 | 23 | 30 | 45 |
|---|
| 8 × 8 | 0.99 | 45 | 60 | 89 |
|---|
| 10 × 10 | 1.54 | 70 | 93 | 139 |
|---|
| 10 × 12 | 1.85 | 84 | 112 | 167 |
|---|
| 12 × 12 | 2.22 | 100 | 134 | 200 |
|---|
| 12 × 16 | 2.96 | 134 | 178 | 267 |
|---|
| 12 × 20 | 3.70 | 167 | 223 | 334 |
|---|
| 16 × 16 | 3.95 | 178 | 238 | 356 |
|---|
| 20 × 20 | 6.17 | 278 | 371 | 556 |
|---|
| 24 × 24 | 8.89 | 400 | 534 | 800 |
|---|
6" thick slabs
6" thick slabs| Slab (ft) | Cubic yards | 80 lb bags | 60 lb bags | 40 lb bags |
|---|
| 4 × 4 | 0.30 | 14 | 18 | 27 |
|---|
| 4 × 8 | 0.59 | 27 | 36 | 54 |
|---|
| 8 × 8 | 1.19 | 54 | 72 | 107 |
|---|
| 10 × 10 | 1.85 | 84 | 112 | 167 |
|---|
| 10 × 12 | 2.22 | 100 | 134 | 200 |
|---|
| 12 × 12 | 2.67 | 120 | 160 | 240 |
|---|
| 12 × 16 | 3.56 | 160 | 214 | 320 |
|---|
| 12 × 20 | 4.44 | 200 | 267 | 400 |
|---|
| 16 × 16 | 4.74 | 214 | 285 | 427 |
|---|
| 20 × 20 | 7.41 | 334 | 445 | 667 |
|---|
| 24 × 24 | 10.67 | 480 | 640 | 960 |
|---|
Bags per cubic yard
Bags per cubic yard| Cubic yards | 80 lb bags | 60 lb bags | 40 lb bags |
|---|
| 0.25 | 12 | 15 | 23 |
|---|
| 0.5 | 23 | 30 | 45 |
|---|
| 0.75 | 34 | 45 | 68 |
|---|
| 1 | 45 | 60 | 90 |
|---|
| 1.5 | 68 | 90 | 135 |
|---|
| 2 | 90 | 120 | 180 |
|---|
| 3 | 135 | 180 | 270 |
|---|
Rounding and how to use the chart
Cubic yards are rounded to two decimals. Bags are rounded up to whole bags, the same as in the calculator: a 10 × 10 ft slab 4" thick is 33.33 cu ft, and 33.33 ÷ 0.60 = 55.6, so 56 bags of 80 lb.
A cubic yard is 45 bags of 80 lb; past about a yard, many crews order ready-mix instead. For a size or thickness that is not listed, a round post hole, or waste added in, use the concrete calculator.
Estimates only. Check measurements, product labels and local building codes before you buy or build.