Cubic Metre Calculator — m³, Litres & Cubic Feet
Calculate cubic metres (m³) from length, width and depth/height, with automatic results in litres and cubic feet.
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How to calculate cubic metres (m³)
For a rectangular volume, multiply the length × width × depth or height, with all three measurements expressed in metres. The result is the volume in cubic metres (m³).
Worked example: 2 m × 1.5 m × 0.5 m
Converting millimetres or centimetres before calculating volume
Do not multiply mixed units. Convert every dimension to metres first. For example, 100 mm = 0.1 m and 50 cm = 0.5 m. If your measurements are in several units, use the Builder Length Converter before calculating the volume.
For a step-by-step explanation, see the How to Calculate Cubic Metres guide.
Square metres and cubic metres are not the same
m² measures area
Square metres describe a two-dimensional surface such as a floor or wall. Use the Floor Area Calculator or Wall Area Calculator when you only need area.
m³ measures volume
Cubic metres add a third dimension — depth or height — which is why they are used for concrete, excavation, soil, screed and other volumetric quantities.
Thickness changes area into volume
If you know an area in m² and a layer depth, convert the depth to metres and multiply area × depth to get m³.
How many litres are in a cubic metre?
1 cubic metre = 1,000 litres. The calculator shows the litre result automatically. This is useful when comparing large-volume site quantities with smaller product or container units.
How to calculate irregular volumes
For stepped, L-shaped or otherwise irregular volumes, split the shape into simple rectangular sections. Calculate the cubic metres of each section separately, then add the results. This is usually more reliable than estimating one oversized bounding box.
Using cubic metres for building materials
The geometric volume is often only the first step. Different materials need different follow-on calculations:
- Concrete: use the Concrete Volume Calculator or Ready-Mix Concrete Cost Calculator.
- Excavation: use the Excavation Volume Calculator because loose spoil can differ from in-situ volume.
- Aggregate: use the Aggregate Calculator to convert volume to tonnes using an explicit bulk density.
- Screed: use the Floor Screed Calculator for layer-specific quantity planning.
- Topsoil: use the Topsoil Calculator for area × depth plus ordering allowance.
Common cubic-metre mistakes
- Entering 100 mm as 100 m instead of 0.1 m.
- Confusing square metres (m²) with cubic metres (m³).
- Using one bounding rectangle for an irregular shape and overestimating the volume.
- Adding a waste or bulking factor before establishing the true geometric volume.
- Using cubic metres as though they directly equal tonnes without checking material density.
Planning estimate only. This calculator gives geometric volume. Product density, compaction, bulking, waste, pack sizes and structural requirements are separate considerations.
Frequently asked questions
How do I calculate cubic metres?
Multiply length by width by depth or height, with all three measurements in metres. The result is in cubic metres (m³).
How many litres are in 1 cubic metre?
One cubic metre equals exactly 1,000 litres.
How do I convert millimetres to metres for a volume calculation?
Divide millimetres by 1,000. For example, 100 mm = 0.1 m.
How do I calculate cubic metres from square metres?
Multiply the area in square metres by the layer depth in metres. For example, 20 m² at 0.1 m deep is 2 m³.
Is a cubic metre the same as a tonne?
No. Cubic metres measure volume and tonnes measure mass. Converting between them requires the relevant material density.
How do I calculate an irregular volume?
Split the shape into simple rectangular sections, calculate each section separately, then add the cubic-metre results.
Related measuring tools
For area-only measurements, use the Floor Area Calculator or Wall Area Calculator. For the full set of geometry and conversion tools, return to the Measuring & Conversions hub.