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, you should seriously consider ready-mix delivery instead.
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. Get a quote before defaulting to bags; the price difference is usually smaller than people expect.
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.