Concrete calculator
Concrete Slab Cost Calculator
Multiply slab area by an installed price range, then add explicit finish, reinforcement, demolition, or fixed extras. The calculator also estimates the concrete order separately.
Planning estimate, not a contractor quote. Review the assumptions and replace presets with local prices when available.
Method
How this calculator works
Installed slab cost is not the price of concrete alone. Excavation, base preparation, forms, reinforcement, finishing, access, crew size, and local labor affect the quote. Calcstead starts with an editable national planning range so the estimate can be replaced with a local rate.
Area = length × width. Installed range = area × (base rate + per-square-foot add-ons) + fixed extras. Concrete volume = length × width × thickness, plus material allowance and quarter-yard ordering round-up.
Worked example
A realistic starting point
A 20 ft by 20 ft slab has 400 ft². At editable rates of $6, $9, and $12 per ft², the planning range is $2,400–$4,800 with a $3,600 midpoint. A 4 in slab with 10% allowance calls for about 5.50 yd³.
What changes the answer
Factors worth checking
Base and site preparation
Excavation, compacted aggregate, drainage, soft soil, and haul-off can materially change the installed price.
Reinforcement
Fiber, welded wire, or rebar should be priced explicitly. Requirements depend on the design and loads.
Finish and edges
Broom finish, exposed aggregate, color, stamping, thickened edges, and control-joint work add labor and material.
Access and minimum charges
Pump trucks, long wheelbarrow routes, small-job minimums, and limited working space can raise the quote.
Common questions
Concrete slab cost FAQ
What does a concrete slab cost per square foot?
There is no universal rate. Use the editable low, typical, and high fields with current local bids or supplier-backed assumptions.
Does thickness change the installed price?
It changes concrete quantity directly, but labor and site costs do not rise in the same proportion. Adjust the installed rate when thickness or reinforcement differs from the base quote.
Is demolition included?
Not in the default range. Add demolition as a per-square-foot or fixed extra after checking access and disposal requirements.
Can I use this for a structural foundation?
The calculator can estimate simple volume and planning cost, but it does not design foundations, footings, reinforcement, or bearing conditions.
Evidence
Sources & review
- NRMCA — Concrete in PracticeConcrete practice and specification context.
- Angi Concrete Slab Cost GuideMarket context used to sanity-check the editable national planning range.
Published by Calcstead. Report a correction.
Method and source links reviewed September 4, 2026. Price presets are editable planning inputs and should be replaced with current local information.