Concrete Cost Calculator
Enter your measurements
Extra to cover cuts, breakage, and mistakes.
Results
- Concrete needed1.36 cubic yards
- Volume36.67 cubic feet
- 60 lb bags82if mixing by bag
- 80 lb bags62if mixing by bag
Estimated cost
per cubic yard of ready-mix, delivered
Material range is per cubic yard of ready-mix delivered, before short-load fees or additives. Installed cost is per square foot of a finished 4-inch slab, including forms, a compacted gravel base, labor to place and finish, and basic curing.
Estimate only — prices vary by region, supplier, and season. Get a local quote before buying.
The concrete cost calculator estimates how much concrete you need for a slab or pad — in cubic yards and bag counts — along with a material price range so you can budget before calling a ready-mix plant or buying bags. Enter your slab's length, width, and thickness, set a waste percentage (10% is standard for most flatwork), and the calculator converts the volume to cubic yards and tells you exactly how many 60 lb or 80 lb bags you would need if mixing by hand. A few things matter before you start. Concrete is sold by the cubic yard when ordered as ready-mix, and one cubic yard fills a space roughly 3 ft × 3 ft × 3 ft, or about 81 square feet at 4 inches thick. Bagged concrete is sold by weight — usually 60 lb or 80 lb sacks — and only stays economical below about half a cubic yard. Standard residential slabs are poured 4 inches thick; driveways and anything carrying vehicle loads call for 6 inches. Plan for at least a 10% overage to cover uneven subgrade, spills, and the concrete that stays in the chute.
How it’s calculated
Volume = Length × Width × Thickness, converted to cubic yards (÷27) and to 60 / 80 lb bag counts.
Worked example
For a 24 ft × 24 ft garage slab at 4 inches thick with a 10% overage, the calculator returns 7.82 cubic yards (211.2 cubic feet) — roughly one ready-mix truck load. If you were mixing by hand instead, that same volume would take about 470 bags of 60 lb mix or 352 bags of 80 lb mix, making it immediately clear why hand-mixing a project this size is impractical compared to ordering a truck.
Inputs
- Length
- 24 ft
- Width
- 24 ft
- Thickness
- 4 in
- Waste / overage
- 10 %
Result
- Concrete needed
- 7.82 cubic yards
- Volume
- 211.2 cubic feet
- 60 lb bags
- 470
- 80 lb bags
- 352
- Estimated material cost
- $1,095 – $1,447
Materials & pricing near you
Ready-mix concrete is delivered by the cubic yard, and most plants set a minimum order of 1 yard, with short-load fees of roughly $50–$150 added below about 5 yards. Material price varies by haul distance: jobs far from a batch plant pay fuel surcharges, while dense metro markets with several competing plants tend toward the low end. Price also climbs in spring and early summer, the peak pour season across most of the US. A higher-strength mix (4,000 PSI instead of a standard 3,000 PSI driveway or patio mix) and fiber or air-entraining additives each raise the per-yard price. Bagged concrete at home centers runs about $6–$9 per 80 lb bag, and since one cubic yard takes roughly 45 bags, ready-mix wins on price for anything past about half a yard.
Frequently asked questions
How thick should a concrete slab be?
A standard residential patio or walkway is poured 4 inches thick. Driveways and any slab that will carry vehicle traffic should be at least 6 inches. Footings and structural slabs engineered to a load spec with rebar may require 8 inches or more. Check local building codes — many municipalities require a permit and inspection for slabs over a certain square footage.
How many cubic yards do I need for a 24x24 slab?
A 24 ft × 24 ft slab at 4 inches thick is 192 cubic feet, which is 7.11 cubic yards of concrete. With a standard 10% waste allowance, the total rises to 7.82 cubic yards. The formula is (length × width × thickness, all in feet) ÷ 27, then multiplied by 1.10 for overage.
Is it cheaper to use bags or order ready-mix?
Ready-mix is almost always cheaper per cubic yard once a project is larger than about a third to half a yard. One cubic yard takes roughly 45 bags of 80 lb mix, so at $6–$9 per bag that is $270–$405 in bags versus about $140–$185 for delivered ready-mix — two to three times more. Bags make sense for small repairs, fence posts, and a handful of footings where a truck minimum would mostly go to waste.
What is the 10% waste factor for, and should I use more?
The overage covers uneven subgrade that consumes more concrete than the nominal slab thickness, minor spills, and the mix that sticks to the drum and chute. Ten percent is standard for flat slab work. Bump it to 15% if your subgrade is rough or your forms are not perfectly level, and use 15–20% for irregularly shaped or decorative slabs where trimming and edge waste run higher.