Concrete Patio Calculator
A patio is a 4″ slab on 4″ of compacted stone, with control joints every 8–10 ft. Enter the finished patio size; anything over about 1 yard is a ready-mix job, under that bags are practical.
Order 2.00 yd³ ready-mix — plants ticket in ¼-yd³ and most charge a short-load fee under ~5 yd³.
- Net volume (48.0 ft³)
- 1.78 yd³
- Waste 10%
- + 0.18 yd³
- Ready-mix ticket
- 2.00 yd³
- Approx. weight
- 7,200 lb
- 80 lb bags
- 88
- 60 lb bags
- 118
- 40 lb bags
- 176
- Materials + delivery$125–$180 / yd³ · Sep 2026
- $350 – $460
- Installed (with labor)typ. $1,120
- $782 – $1,612
Quantities follow the ticket. Links may earn us a commission at no cost to you; they never change a number.
What will this concrete job cost?
See the installed price range for these quantities and get up to 3 quotes from local contractors. Free, no obligation. Also: Driveway cost.
How to calculate concrete by hand
Cubic yards = Length (ft) × Width (ft) × Thickness (in) ÷ 12 ÷ 27 · 80 lb bags = ft³ ÷ 0.60
Worked example
- Area: 20 ft × 17 ft = 340 ft².
- Volume: 340 ft² × (4 in ÷ 12) = 113.3 ft³ = 4.20 yd³.
- Waste 10%: 113.3 × 1.10 = 124.7 ft³ = 4.62 yd³ → ready-mix ticket 4.75 yd³.
- Bags instead: 124.7 ÷ 0.60 = 208 × 80 lb bags (or 277 × 60 lb, 416 × 40 lb).
- Above 1 yd³, ready-mix costs less than bags even with a short-load fee — order the truck.
- 1 yd³ of concrete
- 45 × 80 lb · 60 × 60 lb · 90 × 40 lb bags
- 1 yd³ at 4″ thick
- ≈ 81 ft²
- 1 yd³ at 6″ thick
- ≈ 54 ft²
- 80 lb bag yield
- 0.60 ft³ · ≈ 1.8 ft² at 4″
Questions crews ask
How much concrete for a 12x12 patio?
144 ft² × 4″ = 48 ft³ = 1.78 yd³; with 10% waste 1.96 yd³ → order 2 yards ready-mix, or 88 × 80 lb bags if you are determined to mix it.
How many bags of concrete for a 10x10 patio?
33.3 ft³ plus 10% = 36.7 ft³ → 62 × 80 lb bags, 82 × 60 lb or 123 × 40 lb. That is right at the 1-yard line where a short load of ready-mix costs about the same and saves a day of mixing.
Does a patio slab need rebar?
A 4″ patio on a good base needs wire mesh or fibre mix, not rebar. Use #3 or #4 rebar on 18″ centres if it will carry a hot tub or the soil is expansive clay.