Concrete for a 26×40 slab
12.84 cubic yards (636 × 80 lb bags)
for a 26×40 ft slab 4 inches thick: 346.7 cu ft. Bag counts include 10% extra; at 6 inches you need 19.26 yards.
A 26×40 foot slab covers 1040 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 346.7 cubic feet of concrete, or 12.84 cubic yards. At this size ready-mix is cheaper and far less work than bags: about 14.25 yards, roughly $2,351 before delivery fees, against $4,134 for 636 bags of 80 lb mix.
Concrete for a 26×40 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 9.63 | 260 | 477 | 636 | 954 |
| 4 in | 12.84 | 346.7 | 636 | 848 | 1272 |
| 5 in | 16.05 | 433.3 | 795 | 1060 | 1589 |
| 6 in | 19.26 | 520 | 954 | 1272 | 1907 |
| 8 in | 25.68 | 693.3 | 1272 | 1695 | 2543 |
Bag counts include 10% extra for spillage and uneven ground. Cubic yards and cubic feet are the exact volume.
How it’s worked out
- Convert the thickness to feet: 4 in ÷ 12 = 0.333 ft.
- Multiply length × width × thickness: 40 × 26 × 0.333 = 346.67 cu ft.
- Divide by 27 for cubic yards: 346.67 ÷ 27 = 12.84 cu yd.
- Add 10% and divide by the bag yield: 381.33 ÷ 0.6 = 636 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 12.84 cubic yards. For driveways and anything that carries a vehicle, go to 5 or 6 inches and add rebar or wire mesh.
Change the numbers
Other slab sizes
- 25×40 slab
- 24×40 slab
- 28×40 slab
- 26×36 slab
- 22×40 slab
- 30×40 slab
- 26×32 slab
- 20×40 slab
- 32×40 slab
- 26×30 slab
- 26×50 slab
- 26×28 slab
Questions
- How many bags of concrete do I need for a 26×40 slab?
- At 4 inches thick, a 26×40 slab takes 636 bags of 80 lb concrete mix, 848 bags of 60 lb mix or 1272 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 26×40 slab?
- 12.84 cubic yards at 4 inches thick, 16.05 at 5 inches and 19.26 at 6 inches, before adding extra for waste.
- How much does a 26×40 concrete slab cost?
- The concrete alone for a 4 inch 26×40 slab costs about $4,134 in 636 bags of 80 lb mix (at about $7 a bag) or about $2,351 for 14.25 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $6,240 to $12,480 for 1040 sq ft.
- How much does a 26×40 slab weigh?
- About 25.1 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).