Concrete for a 28×50 slab
17.28 cubic yards (856 × 80 lb bags)
for a 28×50 ft slab 4 inches thick: 466.7 cu ft. Bag counts include 10% extra; at 6 inches you need 25.93 yards.
A 28×50 foot slab covers 1400 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 466.7 cubic feet of concrete, or 17.28 cubic yards. At this size ready-mix is cheaper and far less work than bags: about 19.25 yards, roughly $3,176 before delivery fees, against $5,564 for 856 bags of 80 lb mix.
Concrete for a 28×50 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 12.96 | 350 | 642 | 856 | 1284 |
| 4 in | 17.28 | 466.7 | 856 | 1141 | 1712 |
| 5 in | 21.6 | 583.3 | 1070 | 1426 | 2139 |
| 6 in | 25.93 | 700 | 1284 | 1712 | 2567 |
| 8 in | 34.57 | 933.3 | 1712 | 2282 | 3423 |
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 × 28 × 0.333 = 466.67 cu ft.
- Divide by 27 for cubic yards: 466.67 ÷ 27 = 17.284 cu yd.
- Add 10% and divide by the bag yield: 513.33 ÷ 0.6 = 856 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 17.28 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
- 26×50 slab
- 30×50 slab
- 25×50 slab
- 24×50 slab
- 32×50 slab
- 28×40 slab
- 22×50 slab
- 28×36 slab
- 20×50 slab
- 36×50 slab
- 18×50 slab
- 28×32 slab
Questions
- How many bags of concrete do I need for a 28×50 slab?
- At 4 inches thick, a 28×50 slab takes 856 bags of 80 lb concrete mix, 1141 bags of 60 lb mix or 1712 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 28×50 slab?
- 17.28 cubic yards at 4 inches thick, 21.6 at 5 inches and 25.93 at 6 inches, before adding extra for waste.
- How much does a 28×50 concrete slab cost?
- The concrete alone for a 4 inch 28×50 slab costs about $5,564 in 856 bags of 80 lb mix (at about $7 a bag) or about $3,176 for 19.25 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $8,400 to $16,800 for 1400 sq ft.
- How much does a 28×50 slab weigh?
- About 33.8 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).