Floors & Walls

Concrete Calculator

Find concrete volume for a slab, wall or cylindrical footing, with optional bag yield and cost.

Units

Your measurements

Results update as you type.

Example shown — use your own measurements.

Extra options & cost (optional)

Applied once. Choose an allowance for your project; zero adds no extra material.

Enter mixed concrete yield, not bag weight. No universal bag yield is assumed.

Fractions and number formats

Use decimals (12.5), fractions (12 1/2 or 12-1/2), or explicit lengths (12ft 6in, 12′ 6″, 25 mm). A comma followed by one or two digits is a decimal comma: 12,5 = 12.5. Grouped commas mean thousands: 1,200 = 1200. Use a decimal point for ambiguous values. Scientific notation is not accepted.

Enter your measurements

Results update as you type.

About this calculator

Find concrete volume for a slab, wall or cylindrical footing, with optional bag yield and cost. Enter your measurements and check the worked example below. Product quantities use the label information you supply.

How to measure

  • Measure the actual usable surface or internal space, using the field labels for the selected mode.
  • Keep openings and excluded areas separate so they are subtracted once.
  • Recheck units and label coverage before ordering.
1. Length2. Width3. Depth / thickness
Measurement guide, not to scale. Follow the field labels for the selected mode.

How to use this calculator

  1. Choose slab, wall or cylinder and enter the matching dimensions.
  2. Add an extra-material allowance once if your project needs it.
  3. For bags, enter mixed yield from the exact product label; for ready-mix cost, select the matching volume price basis.
  4. Compare net and order volume; structural dimensions and mix selection come from the project design.

Formula

Slab / wall volume = length × width × thickness or height

Cylindrical volume = π × diameter² × height ÷ 4

Order = net volume × (1 + extra / 100); bags = ceiling(order / label mixed yield)

Assumptions

  • The selected geometry has uniform dimensions; cylinders use internal diameter and height.
  • Mixed yield and any price must match the exact product or quoted volume basis.
  • Extra volume is applied once; bag purchases round up from the unrounded order volume.

Common mistakes

  • Applying the same allowance in both measurements and the extra-material field.
  • Entering coverage or yield from a different product or measurement basis.
  • Treating a quantity estimate as an installation or structural approval.

Worked example

Try it: press “Load example” above the form.

A 10 × 12 ft slab at 4 in is 40 ft³, or 1.481481… yd³, before allowance.

Limitations

This estimates volume only. Strength, reinforcement, loads, formwork, footing dimensions, curing and placement need an appropriate project design. Material cost excludes delivery, labor, fees and tax.

Frequently asked questions

Can bag weight replace mixed concrete yield?

No. Bags are counted from the mixed volume yielded by the exact product, not its dry mass. Leave bag yield blank for a volume-only estimate; enter the label’s mixed yield for whole bags.

What does the worked example show?

A 10 × 12 ft slab at 4 in is 40 ft³, or 1.481481… yd³, before allowance.

Are ready-mix and bag costs the same estimate?

No. Ready-mix cost uses the volume price basis you select; bag cost uses whole bags and price per bag. Delivery, minimum orders, labour, fees and tax need separate quotes.

Does this approve footing dimensions or concrete strength?

This estimates volume only. Strength, reinforcement, loads, formwork, footing dimensions, curing and placement need an appropriate project design. Material cost excludes delivery, labor, fees and tax.

Reviewed by Codex AI editorial agent (Editorial, 2026-11-12).

Sources

Sources explain the methods and any named product presets. Check your product label where coverage, yield or density differs.

Calculation documentation · Updated 2026-11-11 · Version 1.6.4. Estimates are planning aids. Confirm quantities, coverage and prices with your supplier before purchasing. Found an error? Report it.

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