Free Concrete calculator
Estimate concrete for slabs, footings, post holes, and solid steps. Compare concrete mix bags with ready-mix volume and truckloads.
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Concrete calculator
Estimate concrete for slabs, footings, post holes, and solid steps. Compare concrete mix bags with ready-mix volume and truckloads.
Open concrete calculatorResults update as valid measurements are entered. Check product coverage and the assumptions shown with your results.
How to estimate concrete
- Choose a rectangular or circular slab, footing pads, continuous footing, cylindrical post holes, or concrete steps.
- Enter the dimensions shown for that shape. Thickness and depth use inches in US mode; project lengths use the units beside each field.
- Choose bagged concrete mix or ready-mix delivery. For bags, select a listed mix size or enter a custom labeled yield. For delivery, enter usable volume per truck.
- Check the waste allowance and read the purchase quantity. The embed updates when the required inputs are valid.
Read volume, bags, and truckloads separately
For a rectangular pour, volume is length × width × thickness, with all three measurements converted to the same unit. Divide cubic feet by 27 for cubic yards. The calculator adds your waste allowance before dividing by bag yield or truck capacity.
For example, a fictional 10 × 12 ft slab at 4 inches thick contains 40 cubic feet before waste. A 10% allowance makes 44 cubic feet. At an entered yield of 0.6 cubic feet per bag, the order rounds up to 74 bags.
Ready-mix mode shows the adjusted order volume, truck count, and remaining volume on the final load. Order the calculated concrete volume, rather than multiplying every truck by its maximum capacity.
Match the model to the pour
The steps model assumes solid stairs on a level base. It excludes landings, hollow undersides, and foundations. This is a quantity estimate, not a specification for concrete strength, reinforcement, or footing design. Confirm the mix yield or delivery capacity with your supplier. US and metric measurement modes are available.
Keep the material allowance with the job
Use the quantity estimate to check supplier costs before you price the work.
Cinderblock keeps estimates, invoices, notes, and files with the job. The Build plan adds job costing from labor, materials, purchase orders, and manually entered costs. Calculator inputs do not transfer into Cinderblock automatically.
Concrete questions
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