How Much Concrete for a 12×16 Slab?
Quick Answer
A 12×16 foot slab poured 4 inches thick needs 2.37 cubic yards of concrete. Order about 2.6 cubic yards to cover a 10% waste factor. At this size, ready-mix delivery is far more practical than bags.
- 4-inch slab: 2.37 cubic yards (64 cubic feet)
- Order ~2.6 cubic yards with 10% waste
- Bag equivalent: ~107 80-lb bags or ~143 60-lb bags
- Ready-mix cost: $355–$455 delivered
Formula
Multiply length, width, and thickness (in feet) to get cubic feet, then divide by 27 to convert to cubic yards. For a 4-inch slab, thickness is 4 ÷ 12 = 0.333 ft.
Step-by-Step Calculation
- 1
Slab volume in cubic feet
12 × 16 × 0.333 = 64 cubic feet
- 2
Convert to cubic yards
64 ÷ 27 = 2.37 cubic yards
- 3
Add 10% waste
2.37 × 1.10 = 2.6 cubic yards
- 4
Bag equivalent (80-lb)
64 ÷ 0.6 cu ft per bag = 107 bags
12×16 Slab Concrete by Thickness
| Thickness | Cubic Feet | Cubic Yards | 80-lb Bags | Ready-Mix Cost* |
|---|---|---|---|---|
| 4 inches | 64 | 2.37 | 107 | $355–$415 |
| 5 inches | 80 | 2.96 | 134 | $445–$520 |
| 6 inches | 96 | 3.56 | 160 | $535–$625 |
*Ready-mix at $150–$175 per cubic yard delivered. Add short-load fees for orders under 3 cubic yards.
Frequently Asked Questions
How many bags of concrete for a 12×16 slab?
A 4-inch 12×16 slab needs about 107 80-lb bags or 143 60-lb bags. That is a lot of mixing — at roughly 60 or more bags, ready-mix delivery is cheaper and far less labor.
How thick should a 12×16 slab be?
Four inches is standard for patios, sheds, and walkways. Use 5 to 6 inches if the slab will support vehicles, heavy equipment, or a garage. Always pour over 4 inches of compacted gravel.
How much does a 12×16 concrete slab cost?
Materials run $355–$625 depending on thickness. A professionally poured and finished 12×16 slab costs $1,150–$2,300 (about $6–$12 per sq ft) including labor, forms, and finishing.