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Concrete Volume

Slab volume in cubic meters and approximate weight.

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Calculate concrete, rebar, paint, tiles and air-conditioning capacity.

The concrete calculator estimates the volume of a rectangular slab, footing or similar element and its approximate mass. Enter length and width in meters, thickness in centimeters and the concrete density you want to use. The density is editable so the estimate can reflect the material assumption appropriate to your project.

How it works

Measure the concrete element's length and width in meters and enter its thickness in centimeters. Enter the assumed concrete density in kilograms per cubic meter. The calculator converts the thickness from centimeters to meters, calculates the rectangular volume, then multiplies that volume by the entered density to estimate mass.

The formula

Volume (m³) = length (m) × width (m) × thickness (cm) ÷ 100. Approximate mass (kg) = volume (m³) × concrete density (kg/m³).

Length and width describe the plan dimensions of the rectangular element. Thickness is entered in centimeters and divided by 100 to convert it to meters. Density is an editable material assumption; the default value in the calculator is 2400 kg/m³. The result does not automatically add ordering waste, over-excavation, uneven subgrade, pump loss or other site allowances.

Worked example

For a slab 5 m long, 4 m wide and 20 cm thick, the volume is 5 × 4 × 20 ÷ 100 = 4.00 m³. If the entered density is 2400 kg/m³, the approximate mass is 4 × 2400 = 9,600 kg.

This is a quantity estimate, not a structural design calculation. Irregular geometry, openings, slopes, beams, foundations and site losses should be measured separately before ordering material.

Frequently asked questions

Why is thickness entered in centimeters?

The user interface accepts thickness in centimeters because slab thickness is commonly specified that way. The calculator divides the entered value by 100 before calculating cubic meters.

Is 2400 kg/m³ always the correct concrete density?

No. It is the calculator's editable default assumption. Actual density varies with mix design, aggregate and concrete type, so use a project-appropriate value when known.

Does the result include concrete waste?

No. The calculated volume is the geometric rectangular volume only. Add any ordering, pumping or site contingency separately according to project conditions.

Last content reviewAugust 8, 2026
Editorial reviewHe-Sab Editorial Review

Sources and references

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