How Much Concrete for a 16x16 Slab?
A 16×16 ft slab covers 256 sq ft. At the standard 4-inch thickness it needs 3.16 cubic yards of concrete – about 157 bags of 80 lb mix including 10% extra. Adjust the thickness below for your project.
Concrete for a 16x16 slab by thickness
| Thickness | Cubic yards | Yards +10% | 80 lb bags | 60 lb bags | Ready-mix cost* |
|---|---|---|---|---|---|
| 4 in | 3.16 | 3.48 | 157 | 209 | $574 |
| 5 in | 3.95 | 4.35 | 196 | 261 | $717 |
| 6 in | 4.74 | 5.21 | 235 | 313 | $860 |
*At about $165 per cubic yard before delivery and short-load fees. Bag counts include 10% extra.
How it is calculated
16 ft × 16 ft × (4 in ÷ 12) = 85.3 cu ft
85.3 cu ft ÷ 27 = 3.16 cubic yards
80 lb bags = 85.3 × 1.10 ÷ 0.60 = 157
Which thickness do you need?
- 4 inches – patios, walkways, shed floors and most residential garage floors.
- 5–6 inches – driveways, hot tub pads, and garages for heavier trucks or RVs.
- Add 4–6 inches of compacted gravel base underneath and use rebar or wire mesh for slabs larger than about 10×10 ft.
Frequently asked questions
How many yards of concrete for a 16x16 slab?
A 16x16 slab (256 sq ft) needs 3.16 cubic yards at 4 inches thick, 3.95 yd³ at 5 inches and 4.74 yd³ at 6 inches, before waste.
How many bags of concrete for a 16x16 slab?
At 4 inches thick with 10% extra, you need about 157 bags of 80 lb concrete mix or 209 bags of 60 lb mix.
Should I use bags or ready-mix for a 16x16 slab?
At 3.5 cubic yards, ready-mix delivery is usually faster and more consistent than mixing 157 bags by hand. Many suppliers charge a short-load fee under 3–4 yards.