Concrete for a 3×26 slab
0.96 cubic yards (48 × 80 lb bags)
for a 3×26 ft slab 4 inches thick: 26 cu ft. Bag counts include 10% extra; at 6 inches you need 1.44 yards.
A 3×26 foot slab covers 78 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 26 cubic feet of concrete, or 0.96 cubic yards. At this size you can mix 48 bags of 80 lb (about $312 and a long day of mixing) or order 1.25 yards of ready-mix (about $206, plus the short-load fee most suppliers charge under 3 to 4 yards).
Concrete for a 3×26 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 0.72 | 19.5 | 36 | 48 | 72 |
| 4 in | 0.96 | 26 | 48 | 64 | 96 |
| 5 in | 1.2 | 32.5 | 60 | 80 | 120 |
| 6 in | 1.44 | 39 | 72 | 96 | 143 |
| 8 in | 1.93 | 52 | 96 | 128 | 191 |
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: 26 × 3 × 0.333 = 26 cu ft.
- Divide by 27 for cubic yards: 26 ÷ 27 = 0.963 cu yd.
- Add 10% and divide by the bag yield: 28.6 ÷ 0.6 = 48 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 0.96 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
- 3×25 slab
- 3×24 slab
- 3×28 slab
- 3×22 slab
- 3×30 slab
- 3×20 slab
- 3×32 slab
- 3×18 slab
- 4×26 slab
- 3×16 slab
- 3×36 slab
- 3×15 slab
Questions
- How many bags of concrete do I need for a 3×26 slab?
- At 4 inches thick, a 3×26 slab takes 48 bags of 80 lb concrete mix, 64 bags of 60 lb mix or 96 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 3×26 slab?
- 0.96 cubic yards at 4 inches thick, 1.2 at 5 inches and 1.44 at 6 inches, before adding extra for waste.
- How much does a 3×26 concrete slab cost?
- The concrete alone for a 4 inch 3×26 slab costs about $312 in 48 bags of 80 lb mix (at about $7 a bag) or about $206 for 1.25 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $468 to $936 for 78 sq ft.
- How much does a 3×26 slab weigh?
- About 1.9 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).