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Concrete Calculator

Estimate concrete volume for slabs, footings or walls from length, width and depth, plus a waste factor for site placement.

Estimates only — not professional financial, medical, legal or engineering advice. Read full disclaimer.

Result

Fill in the form and click Calculate to see your result here.

How it's calculated

Volume = L × W × D (converted to metres), then × (1 + wastage). Shape extras are not auto-detected.

Example

Example: Concrete Calculator

Inputs

  • Length: 5
  • Width: 4
  • Thickness: 0.15
  • Cement Ratio: 1
  • Sand Ratio: 2
  • Aggregate Ratio: 4
  • Water Cement Ratio: 0.45

Outputs

  • Concrete Volume: 3
  • Cement Bags: 20
  • Sand Volume: 1.32
  • Aggregate Volume: 2.64
  • Water Required: 427.68

This example uses typical sample values. Adjust the inputs above to see how the results change for your own numbers.

About this calculator

Ready-mix and site-mix both start from cubic metres. This calculator multiplies the prism you describe (length × width × depth) and applies wastage for pumped lines and uneven excavation.

A 4-inch topping is not a 100 mm structural slab — convert units once. Footings that step down cannot be one rectangle; split into pours. Pair with cement/sand/aggregate tools for mix ingredients.

Frequently Asked Questions

Length × width × thickness in metres (defaults 5 × 4 × 0.15 m). Plus mix parts (default 1:2:4) to split cement/sand/aggregate/water when those fields are used in the handler.
Yes for L/W/T. 4-inch topping is 0.10 m, not 4. Mixed ft/m is the usual error.
No. Rebar/steel are separate. This is concrete prism volume (and mix quantities).
One rectangle only. Split the pour into prisms and add volumes.
If the handler exposes waste, use it; otherwise add 2–5% yourself for uneven excavation and lines.
Nominal 1:2:4 is a common site mix approximating certain grades; design mix from a lab overrides this page.
If shown, it follows the handler’s water estimate for the mix — not a slump test.
Same volume math. Enter the column’s rectangular equivalent or break into parts.
No. NBC and IS mix design are engineering. This is quantity from dimensions × nominal ratio.
Use it as a check. Batching plants want wet m³ plus their own waste factor.

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