What this calculator actually models
Concrete quantity starts with geometric volume. A slab uses length × width × thickness; a round pier or cylinder uses π × radius² × height. The calculator then converts the result into common ordering units and can add a user-selected waste allowance.
How to use this calculator
Choose slab or cylinder.
Enter dimensions in feet; convert inches to feet when necessary (for example, 4 in = 0.3333 ft).
Add only the waste allowance appropriate to your project and supplier, then verify the volume before ordering.
Where people use it
- •Slabs, pads and small foundations
- •Round piers and posts
- •Early material planning before obtaining a supplier quote
Example: 12 ft × 10 ft × 4 in slab
4 in = 0.3333 ft. The geometric volume is about 40 cu ft, or 1.48 cu yd before any waste allowance.
Assumptions and limits
- •This calculator does not assume a bag yield because bag coverage varies by product and manufacturer. Use the yield printed on the product you will actually buy.
- •Excavation tolerances, subgrade, irregular geometry, overbreak and supplier minimums can change the ordered quantity.
Frequently asked questions
How many cubic feet are in a cubic yard?+
There are exactly 27 cubic feet in one cubic yard.
How do I enter a 4-inch slab thickness?+
Convert inches to feet by dividing by 12. Four inches is approximately 0.3333 ft.
Does this tell me how many bags to buy?+
Not automatically. Use the actual yield stated on the bag because product yields differ.
Semantic next steps
Continue the calculation
These links move to a different input, formula or project stage rather than a keyword variation of this page.
Square Footage Calculator
Calculate square footage for rectangles, circles and triangles, convert the area to square meters and estimate cost from a price per square foot.
OpenFeet and Inches Calculator
Add, subtract, multiply, divide or convert feet and inches, including decimal and fractional inch inputs, with decimal feet and metric equivalents.
OpenBoard Foot Calculator — Lumber Volume & Cost Basis
Calculate board feet from lumber thickness, width, length and quantity, then add an optional waste allowance for a project tally.
OpenGravel Calculator — Cubic Yards & Tons
Estimate gravel volume from length, width and depth, add a project allowance and convert cubic yards to tons using a density you can verify with the supplier.
OpenBrick Calculator — Bricks, Mortar, Cement, Sand & Cost
Estimate bricks for one or more walls after opening deductions, then calculate wet and dry mortar, cement bags, sand volume and optional material cost from actual brick dimensions and mortar-joint inputs.
OpenConcrete Block Calculator — CMU Blocks, Mortar, Grout, Pallets & Cost
Estimate concrete blocks for a wall after opening deductions, then plan mortar bags, pallets and optional core-fill grout from actual block-face dimensions and editable product coverage, void fraction and bag-yield inputs.
OpenTank Volume Calculator — Capacity, Partial Fill, Gallons, Litres & Weight
Calculate total and partial-fill volume for rectangular, vertical-cylinder, horizontal-cylinder, horizontal-elliptical, horizontal-capsule and spherical tanks, with litres, US/Imperial gallons, remaining capacity, liquid weight and optional fill/drain time.
OpenPipe Volume Calculator — Litres, Gallons, Partial Fill, Weight & Fill Time
Calculate pipe internal capacity from actual bore or outside diameter plus wall thickness, including partial horizontal fill, multiple runs, fittings-length allowance, litres/gallons, fluid weight, volume per metre and optional fill/drain time.
OpenMore in this calculator collection
Browse nearby calculators in the same topic cluster so related pages reinforce each other instead of sitting as isolated URLs.
Free publisher widget
Put this calculator on your website
Give readers the live calculator without rebuilding the math. Copy the responsive embed in one click, or customize width, height, border and corner radius before publishing. The branded MAXScanner attribution stays visible.
Keep the result connected to the real job
MAXScanner keeps the formula and assumptions beside the result so you can verify the number before using it in a drawing, estimate, specification, worksheet or document. Where a supplier, manufacturer, drawing or applicable standard owns a requirement, that source remains authoritative.