How Much Concrete for a 16x45 Slab?
A 16 by 45 foot slab is 720 square feet. How much concrete for a 16x45 slab at the common 4-inch thickness: about 8.89 cubic yards. Most people order 10.00 yards to cover waste and an uneven base.
Concrete calculator →The math for a 16x45 slab
- Area: 16 ft × 45 ft = 720 sq ft.
- Thickness in feet: 4 in ÷ 12 = 0.333 ft.
- Volume: 720 × 0.333 = 240.0 cubic feet.
- Cubic yards: 240.0 ÷ 27 = 8.89 yd³.
- With 10% extra: 9.78 yd³.
The concrete calculator runs the same steps for any size and thickness.
Related: How Much Gravel for a 16x45 Driveway?
Concrete for a 16x45 slab by thickness
| Thickness | Cubic feet | Cubic yards | Yards +10% | 80 lb bags | 60 lb bags |
|---|---|---|---|---|---|
| 4 in | 240.0 | 8.89 | 9.78 | 400 | 534 |
| 5 in | 300.0 | 11.11 | 12.22 | 500 | 667 |
| 6 in | 360.0 | 13.33 | 14.67 | 600 | 800 |
Bag counts assume about 0.60 cubic feet per 80 lb bag and 0.45 per 60 lb bag, rounded up.
How thick to pour it
Four inches is the usual thickness for patios, walks and shed floors. Slabs that carry cars or a heavy hot tub are often poured at 5 to 6 inches, and edges are sometimes thickened where loads concentrate.
Related: How Many Tons of Asphalt for a 16x45 Driveway?
Truck or bags?
A cubic yard of concrete is 27 cubic feet and weighs roughly 4,000 pounds. Most ready-mix trucks carry up to about 9 to 10 yards, though local trucks and rules vary. If your total is under a yard or two, bagged mix or a short-load supplier may be cheaper.
Getting the ground ready
Under the slab, most residential pours sit on about 4 inches of compacted gravel. The base spreads the load, drains water away and keeps the slab from cracking as the soil freezes and thaws. Compact the base in thin lifts, and dampen it just before the pour so it does not pull water out of the mix.
Joints, mesh and rebar
Cut or tool control joints so the slab cracks where you want it to. A common rule is spacing them, in feet, at no more than two to three times the slab thickness in inches, so about 10 feet apart for a 4-inch slab, and about a quarter of the slab depth deep.
Questions people ask
How many yards of concrete for a 16x45 slab at 4 inches?
About 8.89 cubic yards, or 9.78 with 10 percent extra.
How many yards for a 16x45 slab at 6 inches?
About 13.33 cubic yards.
How many 80 lb bags for a 16x45 slab?
About 400 bags at 4 inches thick, before any waste allowance.
How many square feet is a 16x45 slab?
720 square feet.
How much does a cubic yard of concrete weigh?
Roughly 4,000 pounds, or about 2 tons, for normal-weight concrete.
When is bagged concrete practical?
Usually for jobs under about a cubic yard. Beyond that, mixing dozens of bags by hand gets slow and batches may not blend well.
Related guides
- How Much Area Does a Yard of Concrete Cover?
- How Many Bags of Concrete in a Yard? 40, 60, 80 lb
- Gravel Base Under a Concrete Slab: Depth and Tons
- How Many Yards in a Concrete Truck? Mixer Sizes
- Concrete Short Load Fee: What It Is and How to Cut It
- 60 lb vs 80 lb Concrete Bags: Yield, Count, and Cost
- Rebar vs Wire Mesh in a Slab: Which One to Use
- Cost to Pour a Concrete Slab: Per Square Foot
- How Much Concrete for a 16x36 Slab?
- How Much Concrete for a 16x40 Slab?
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