Calculators
Concrete calculators that show their work: volume, bags, truckloads, rebar, joints, cost and conversions. Each one states its formula and its assumptions.
Concrete slab calculator
Work out cubic yards, cubic feet and bag counts for a concrete slab. Enter length, width and thickness; includes a waste factor and a metric conversion.
Footing calculator
Calculate concrete volume for a continuous strip footing. Enter width, depth and total run length to get cubic yards, cubic feet and bag counts.
Column & tube calculator
Concrete volume for round column forms and tube footings. Enter diameter, height and quantity to get cubic yards, cubic feet and bag counts.
Bag count calculator
How many bags of concrete you need for a given volume, for 40, 50, 60 and 80 lb bags. Yields are manufacturer figures and vary by formulation.
Truckload & short-load calculator
How many ready-mix trucks a pour needs, whether the last load triggers a short-load fee, and roughly what the material will cost.
Rebar calculator
Total rebar length, bar counts and stick counts for a slab grid at a chosen spacing and cover. Spacing is engineer-specified, not a code default.
Control joint calculator
Control joint spacing and depth for a slab. Spacing in feet is 2 to 3 times the slab thickness in inches; joint depth is 25% of thickness.
Concrete cost estimator
Estimate material and labor cost for a concrete slab. Published price sources disagree substantially, so every figure here is an adjustable estimate.
PSI ⇄ MPa converter
Convert concrete compressive strength between psi and MPa. One megapascal equals 145.04 psi, so 4,000 psi is 27.6 MPa.
Cure timeline calculator
Estimated timeline for foot traffic, vehicles and moist curing based on placement temperature. Cold weather roughly doubles every interval.
Sealer & stain coverage calculator
How much sealer or stain a slab needs. Enter area, coverage rate and coats to get gallons and pail counts. Rates come from the product data sheet.
Gravel base calculator
Base material volume, weight and tonnage under a concrete slab, with a compaction allowance. Enter area and base depth.