How to Calculate Concrete Volume for a Slab
Ordering concrete starts with one multiplication: length times width times depth. Here is how to get the volume right before you call the supplier.
What is the Concrete Volume Calculator?
Multiply length by width by depth, all in metres, to get the volume in cubic metres. The calculator also shows the same volume in litres, since one cubic metre equals 1000 litres, which helps when comparing with bag sizes or mixer capacities.
How to use it
- Enter the length and width of the slab in metres.
- Enter the depth (thickness) in metres.
- Press Calculate to see the volume in cubic metres and litres.
Worked example
Length 5 m, width 3 m, depth 0.15 m: the tool gives 2.25 cubic metres (2250 litres).
How much concrete fills a 5 m by 3 m slab that is 0.15 m thick?
It needs 2.25 cubic metres, because 5 times 3 times 0.15 is 2.25, which is the same as 2250 litres. That is the neat volume, so in practice you would order slightly more to cover uneven ground and spillage.
Frequently asked questions
What if my depth is in centimetres?
Divide centimetres by 100 to get metres first. For example, a 15 cm slab is 0.15 metres deep.
Should I order extra concrete?
Yes, most builders add around 5 to 10 percent for uneven ground and spillage, on top of the calculated volume.