Concrete for a 25×50 slab
15.43 cubic yards (764 × 80 lb bags)
for a 25×50 ft slab 4 inches thick: 416.7 cu ft. Bag counts include 10% extra; at 6 inches you need 23.15 yards.
A 25×50 foot slab covers 1250 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 416.7 cubic feet of concrete, or 15.43 cubic yards. At this size ready-mix is cheaper and far less work than bags: about 17 yards, roughly $2,805 before delivery fees, against $4,966 for 764 bags of 80 lb mix.
Concrete for a 25×50 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 11.57 | 312.5 | 573 | 764 | 1146 |
| 4 in | 15.43 | 416.7 | 764 | 1019 | 1528 |
| 5 in | 19.29 | 520.8 | 955 | 1274 | 1910 |
| 6 in | 23.15 | 625 | 1146 | 1528 | 2292 |
| 8 in | 30.86 | 833.3 | 1528 | 2038 | 3056 |
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: 50 × 25 × 0.333 = 416.67 cu ft.
- Divide by 27 for cubic yards: 416.67 ÷ 27 = 15.432 cu yd.
- Add 10% and divide by the bag yield: 458.33 ÷ 0.6 = 764 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 15.43 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
- 24×50 slab
- 26×50 slab
- 22×50 slab
- 28×50 slab
- 20×50 slab
- 25×40 slab
- 30×50 slab
- 18×50 slab
- 25×36 slab
- 32×50 slab
- 16×50 slab
- 25×32 slab
Questions
- How many bags of concrete do I need for a 25×50 slab?
- At 4 inches thick, a 25×50 slab takes 764 bags of 80 lb concrete mix, 1019 bags of 60 lb mix or 1528 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 25×50 slab?
- 15.43 cubic yards at 4 inches thick, 19.29 at 5 inches and 23.15 at 6 inches, before adding extra for waste.
- How much does a 25×50 concrete slab cost?
- The concrete alone for a 4 inch 25×50 slab costs about $4,966 in 764 bags of 80 lb mix (at about $7 a bag) or about $2,805 for 17 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $7,500 to $15,000 for 1250 sq ft.
- How much does a 25×50 slab weigh?
- About 30.2 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).