How much concrete do I need for a 10×10 slab?
A 10×10 ft slab poured 4 inches thick needs about 1.4 cubic yards of concrete including a 10% allowance — roughly 62 bags of 80-lb mix. At that quantity, it’s worth getting a ready-mix delivery quote before committing to bags — the labor math alone makes it worth the call, even though which one is cheaper depends on your local suppliers.
Your 4″ slab needs about 36.7 cu. ft. of concrete including 10% waste. That’s 62 80 lb bags.
Adjust These Numbers for Your ProjectThe math, step by step
- Slab volume: 10 × 10 × 0.333 = 33.3 cu. ft.
- 10% allowance: 33.3 × 1.1 = 36.7 cu. ft.
- Cubic yards: 36.7 ÷ 27 = 1.36 yd³
- Each bag yields 0.6 cu. ft. → 36.7 ÷ 0.6 = 62 bags
- Assumes a rectangular pour with a level, even thickness.
- Never round down on concrete — running short mid-pour is the expensive mistake.
Sixty-two bags is right at the threshold where mixing by hand stops making sense. Each 80-lb bag has to be lifted, mixed, and placed — that’s two and a half tons of material through a wheelbarrow, and concrete waits for no one: sections poured an hour apart bond poorly (a “cold joint”). Two people with a rented mixer can do it in a long morning. One person with a wheelbarrow can’t, not well.
Ready-mix trucks typically have a 1-yard minimum and a short-load fee under about 3 yards, so a 10×10 slab lands in the awkward zone — but even with the fee, delivered concrete arrives mixed to a consistent strength and gives you one continuous pour. Whether that beats bags on price depends on your local supplier’s short-load fee and bag prices, so it’s worth an actual quote rather than assuming either way.
Don’t skip the 10% allowance to save four dollars of mix. Subgrades are never perfectly level, forms bow slightly, and running short mid-pour is the most expensive concrete mistake there is — a cold joint in the middle of a slab is permanent. Excess is cheap; a do-over is not.
Frequently asked questions
Should I pour a 10×10 slab 4 or 6 inches thick?
4 inches suits patios, walkways, and shed bases. Go 6 inches if it will carry vehicles or heavy point loads — that raises the pour to about 2 cubic yards.
How many 60-lb bags instead of 80-lb?
A 60-lb bag yields about 0.45 cu. ft., so the same slab takes roughly 82 of them. Smaller bags are easier on your back but cost more per cubic foot.
Do I need rebar or mesh in a 10×10 slab?
For patios and sheds, welded wire mesh or fiber-reinforced mix controls cracking; rebar matters for driveways and structural slabs. Local code has the final word.