Concrete Volume Calculator

How to use it: pick a shape, then fill in the three dimension fields - their meaning changes with the shape you choose. For a slab or footing, "length" and "width" are the two plan dimensions and "depth" is thickness. For a rectangular column, the same three fields become width, depth and height. For a cylinder, "length" becomes diameter and "depth" becomes height (the width field is unused).

Formula. Slab and column volume is the product of the three dimensions; a cylinder's volume uses its radius (half the diameter):

Slab / column volume = length × width × depth
Cylinder volume = π × (diameter ÷ 2)² × height

All three dimensions are entered in millimetres; the result is converted to cubic metres (÷ 1e9), US cubic yards (× 1.30795 per m³), and litres (÷ 1e6).

Worked example. With the defaults above (slab, 5000 mm × 3000 mm × 100 mm thick): volume = 5000 × 3000 × 100 = 1,500,000,000 mm³ = 1.500 m³, which is 1.500 × 1.30795 ≈ 1.962 yd³, or 1500 L.

The result above uses these exact values. This snapshot is included when the page is printed so the output can be checked against the original measurements.

Shape

Slab / footing

Length / diameter

5000 mm

Width / depth

3000 mm

Thickness / height

100 mm

Primary result: Volume: 1.500 m3.

• Measure from the datum or reference edge described by this tool, and do not mix inside, outside and centerline dimensions.
• Keep inputs in the displayed units and preserve more precision than the final cutting or purchasing tolerance requires.
• When the result is close to a limit, verify it with a test piece, field measurement, manufacturer drawing or qualified project professional.

This is a pure geometric volume - it does not add an ordering allowance for spillage, formwork deflection, uneven sub-grade or over-excavation, or for rounding up to a ready-mix supplier's minimum load or delivery increment. A commonly used margin is 5-10% on top of the calculated volume; confirm the right allowance with your supplier.

It also doesn't account for rebar/mesh displacement, sloped or stepped footings, or column volume lost to embedded items - for anything other than a simple slab, rectangular column, or plain cylinder, break the pour into these basic shapes and sum the results.