Concrete for a 5×50 slab
3.09 cubic yards (153 × 80 lb bags)
for a 5×50 ft slab 4 inches thick: 83.3 cu ft. Bag counts include 10% extra; at 6 inches you need 4.63 yards.
A 5×50 foot slab covers 250 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 83.3 cubic feet of concrete, or 3.09 cubic yards. At this size ready-mix is cheaper and far less work than bags: about 3.5 yards, roughly $578 before delivery fees, against $995 for 153 bags of 80 lb mix.
Concrete for a 5×50 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 2.31 | 62.5 | 115 | 153 | 230 |
| 4 in | 3.09 | 83.3 | 153 | 204 | 306 |
| 5 in | 3.86 | 104.2 | 191 | 255 | 382 |
| 6 in | 4.63 | 125 | 230 | 306 | 459 |
| 8 in | 6.17 | 166.7 | 306 | 408 | 612 |
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 × 5 × 0.333 = 83.33 cu ft.
- Divide by 27 for cubic yards: 83.33 ÷ 27 = 3.086 cu yd.
- Add 10% and divide by the bag yield: 91.67 ÷ 0.6 = 153 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 3.09 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
- 4×50 slab
- 5×40 slab
- 6×50 slab
- 5×36 slab
- 5×32 slab
- 3×50 slab
- 5×30 slab
- 5×28 slab
- 5×26 slab
- 5×25 slab
- 5×24 slab
- 5×22 slab
Questions
- How many bags of concrete do I need for a 5×50 slab?
- At 4 inches thick, a 5×50 slab takes 153 bags of 80 lb concrete mix, 204 bags of 60 lb mix or 306 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 5×50 slab?
- 3.09 cubic yards at 4 inches thick, 3.86 at 5 inches and 4.63 at 6 inches, before adding extra for waste.
- How much does a 5×50 concrete slab cost?
- The concrete alone for a 4 inch 5×50 slab costs about $995 in 153 bags of 80 lb mix (at about $7 a bag) or about $578 for 3.5 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $1,500 to $3,000 for 250 sq ft.
- How much does a 5×50 slab weigh?
- About 6 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).