Concrete for a 6×36 slab
2.67 cubic yards (132 × 80 lb bags)
for a 6×36 ft slab 4 inches thick: 72 cu ft. Bag counts include 10% extra; at 6 inches you need 4 yards.
A 6×36 foot slab covers 216 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 72 cubic feet of concrete, or 2.67 cubic yards. At this size you can mix 132 bags of 80 lb (about $858 and a long day of mixing) or order 3 yards of ready-mix (about $495, plus the short-load fee most suppliers charge under 3 to 4 yards).
Concrete for a 6×36 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 2 | 54 | 99 | 132 | 198 |
| 4 in | 2.67 | 72 | 132 | 176 | 264 |
| 5 in | 3.33 | 90 | 165 | 220 | 330 |
| 6 in | 4 | 108 | 198 | 264 | 396 |
| 8 in | 5.33 | 144 | 264 | 352 | 528 |
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: 36 × 6 × 0.333 = 72 cu ft.
- Divide by 27 for cubic yards: 72 ÷ 27 = 2.667 cu yd.
- Add 10% and divide by the bag yield: 79.2 ÷ 0.6 = 132 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 2.67 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
- 6×32 slab
- 6×40 slab
- 5×36 slab
- 6×30 slab
- 6×28 slab
- 6×26 slab
- 6×25 slab
- 4×36 slab
- 6×24 slab
- 8×36 slab
- 6×22 slab
- 6×50 slab
Questions
- How many bags of concrete do I need for a 6×36 slab?
- At 4 inches thick, a 6×36 slab takes 132 bags of 80 lb concrete mix, 176 bags of 60 lb mix or 264 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 6×36 slab?
- 2.67 cubic yards at 4 inches thick, 3.33 at 5 inches and 4 at 6 inches, before adding extra for waste.
- How much does a 6×36 concrete slab cost?
- The concrete alone for a 4 inch 6×36 slab costs about $858 in 132 bags of 80 lb mix (at about $7 a bag) or about $495 for 3 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $1,296 to $2,592 for 216 sq ft.
- How much does a 6×36 slab weigh?
- About 5.2 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).