Concrete Calculator

Calculate wet concrete volume for rectangular pours in cubic meters and cubic feet, with a separate wastage allowance and mixed-unit dimensions.

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Results update as you edit. Use decimal points without commas. Costs use the same currency as your entered price.

Your estimate

Wet concrete volume: 1.200000m³
Wet concrete volume (CFT): 42.377600ft³
Wastage-adjusted wet volume: 1.320000m³
Wastage-adjusted wet volume (CFT): 46.615360ft³

Display values are rounded; calculations and costs use unrounded quantities. Tile and box counts always round up. A “<” result is positive but smaller than the displayed decimal precision.

How to use Concrete Calculator

Estimate the wet concrete volume for a rectangular pour from length, width and depth, then add a separate wastage allowance. Enter a shallow depth in millimeters or inches while using meters or feet for the plan dimensions; results are shown in both cubic meters and cubic feet.

Enter the measured dimensions and choose the unit beside each measurement. Quantities and counts must be positive whole numbers.
Adjust any wastage and coverage inputs to match your estimate. Leave optional prices blank if you only need quantities.
Review the results and assumptions below. Copy results includes labels and units; Reset defaults restores the starting example.

Calculation explanation

Formulas

Wet volume = length × width × depth (all converted to meters)
Wastage-adjusted wet volume = wet volume × (1 + wastage / 100)
Cubic feet = cubic meters ÷ 0.028316846592

Assumptions and measurement notes

This is a geometric wet-volume estimate, not a structural design, strength assessment or mix specification.
Only a rectangular, constant-depth pour is modeled. Divide irregular shapes into separate measured sections and add their volumes.
No dry-material factor or cement, sand and aggregate breakdown is assumed. The wastage percentage adds extra wet volume.

Units are normalized before calculation: 1 in = 0.0254 m, 1 ft = 0.3048 m, 1 ft² = 0.09290304 m² and 1 ft³ = 0.028316846592 m³. Decimal arithmetic is retained through quantity rounding; dimensions and prices are limited to 1,000,000,000 per input.

Practical examples

A 4 × 3 m rectangular pour

Input: 4 m × 3 m × 100 mm; 10% wastage
Result: Wet concrete volume: 1.200000 m³; Wastage-adjusted wet volume: 1.320000 m³

The 0.1 m depth gives 1.2 m³ of wet volume. Adding 10% increases the estimate to 1.32 m³.

A pour measured in feet and inches

Input: 10 ft × 8 ft × 4 in; 5% wastage
Result: Wet concrete volume (CFT): 26.666667 ft³; Wastage-adjusted wet volume (CFT): 28.000000 ft³; Wastage-adjusted wet volume: 0.792872 m³

The base volume is 26⅔ ft³. A 5% allowance brings it to exactly 28 ft³, or 0.792871704576 m³.

A smaller 150 mm-deep section

Input: 2 m × 1.5 m × 150 mm; 0% wastage
Result: Wet concrete volume: 0.450000 m³; Wastage-adjusted wet volume: 0.450000 m³

The base and adjusted volumes both equal 0.45 m³ because no extra allowance is selected.

Frequently asked questions

How much wastage should I add for concrete pours?

For standard slabs, footings, and pathways poured against smooth formwork, a 5% to 10% wastage allowance is customary. For uneven subgrades, deep trench excavations, or pump-line residue, contractors typically allow 10% to 15% extra.

Can I enter slab depth in inches or millimeters while entering plan dimensions in feet or meters?

Yes. Each dimension has an independent unit selector. You can enter length and width in meters or feet and depth in millimeters or inches. The calculator normalizes all units and displays the result in both cubic meters (m³) and cubic feet (ft³).

Does this calculate wet placed volume or dry bagged mix?

This calculates wet placed concrete volume. Ready-mix trucks are ordered directly by wet volume (m³ or cubic yards). If hand-mixing pre-blended dry concrete bags, note that dry ingredients compact by approximately 30–35% when water is added.