Concrete for a 16×28 slab
5.53 cubic yards (274 × 80 lb bags)
for a 16×28 ft slab 4 inches thick: 149.3 cu ft. Bag counts include 10% extra; at 6 inches you need 8.3 yards.
A 16×28 foot slab covers 448 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 149.3 cubic feet of concrete, or 5.53 cubic yards. At this size ready-mix is cheaper and far less work than bags: about 6.25 yards, roughly $1,031 before delivery fees, against $1,781 for 274 bags of 80 lb mix.
Concrete for a 16×28 slab by thickness
| Thickness | Cubic yards | Cubic feet | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 3 in | 4.15 | 112 | 206 | 274 | 411 |
| 4 in | 5.53 | 149.3 | 274 | 366 | 548 |
| 5 in | 6.91 | 186.7 | 343 | 457 | 685 |
| 6 in | 8.3 | 224 | 411 | 548 | 822 |
| 8 in | 11.06 | 298.7 | 548 | 731 | 1096 |
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: 28 × 16 × 0.333 = 149.33 cu ft.
- Divide by 27 for cubic yards: 149.33 ÷ 27 = 5.531 cu yd.
- Add 10% and divide by the bag yield: 164.27 ÷ 0.6 = 274 bags of 80 lb mix (rounded up).
Under the slab, plan on 4 inches of compacted gravel: about 5.53 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
- 15×28 slab
- 16×26 slab
- 16×30 slab
- 16×25 slab
- 14×28 slab
- 18×28 slab
- 16×24 slab
- 16×32 slab
- 16×22 slab
- 12×28 slab
- 20×28 slab
- 16×20 slab
Questions
- How many bags of concrete do I need for a 16×28 slab?
- At 4 inches thick, a 16×28 slab takes 274 bags of 80 lb concrete mix, 366 bags of 60 lb mix or 548 bags of 40 lb mix, including 10% extra.
- How many yards of concrete for a 16×28 slab?
- 5.53 cubic yards at 4 inches thick, 6.91 at 5 inches and 8.3 at 6 inches, before adding extra for waste.
- How much does a 16×28 concrete slab cost?
- The concrete alone for a 4 inch 16×28 slab costs about $1,781 in 274 bags of 80 lb mix (at about $7 a bag) or about $1,031 for 6.25 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $2,688 to $5,376 for 448 sq ft.
- How much does a 16×28 slab weigh?
- About 10.8 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).