Concrete for a 24×30 slab
8.89 cubic yards (440 × 80 lb bags)
for a 24×30 ft slab 4 inches thick: 240 cu ft. Bag counts include 10% extra; at 6 inches you need 13.33 yards.
A 24×30 foot slab covers 720 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 240 cubic feet of concrete, or 8.89 cubic yards. At this size ready-mix is cheaper and far less work than bags: about 10 yards, roughly $1,650 before delivery fees, against $2,860 for 440 bags of 80 lb mix.
Concrete for a 24×30 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 6.67 | 180 | 330 | 440 | 660 |
| 4 in | 8.89 | 240 | 440 | 587 | 880 |
| 5 in | 11.11 | 300 | 550 | 734 | 1100 |
| 6 in | 13.33 | 360 | 660 | 880 | 1320 |
| 8 in | 17.78 | 480 | 880 | 1174 | 1760 |
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: 30 × 24 × 0.333 = 240 cu ft.
- Divide by 27 for cubic yards: 240 ÷ 27 = 8.889 cu yd.
- Add 10% and divide by the bag yield: 264 ÷ 0.6 = 440 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 8.89 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
- 25×30 slab
- 24×28 slab
- 24×32 slab
- 22×30 slab
- 26×30 slab
- 24×26 slab
- 20×30 slab
- 24×25 slab
- 28×30 slab
- 24×24 slab
- 24×36 slab
- 18×30 slab
Questions
- How many bags of concrete do I need for a 24×30 slab?
- At 4 inches thick, a 24×30 slab takes 440 bags of 80 lb concrete mix, 587 bags of 60 lb mix or 880 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 24×30 slab?
- 8.89 cubic yards at 4 inches thick, 11.11 at 5 inches and 13.33 at 6 inches, before adding extra for waste.
- How much does a 24×30 concrete slab cost?
- The concrete alone for a 4 inch 24×30 slab costs about $2,860 in 440 bags of 80 lb mix (at about $7 a bag) or about $1,650 for 10 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $4,320 to $8,640 for 720 sq ft.
- How much does a 24×30 slab weigh?
- About 17.4 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).