Cement bags, sand and crush (aggregate) for a slab, footing or column at any mix ratio.
How this works
Wet volume is length x width x depth. Dry materials take about 54% more space, so dry volume = wet x 1.54. That is split by the mix ratio, and cement is 1,440 kg per m³, so one 50 kg bag is 0.0347 m³. M20 (1:1.5:3) needs about 8 bags per m³.
Questions people ask
How do I use the Concrete Calculator?
Fill in the fields, starting with “What are you casting”, “Length” and “Width”, and change any other options that match your home. The answer, a drawing and practical tips update as you type, and the Copy link button saves your numbers in a link you can share.
Is the Concrete Calculator free?
Yes. The Concrete Calculator is free, with no sign-up, and works on phones, tablets and computers. The results are estimates to help you plan, so check with a qualified professional before structural, electrical, gas or plumbing work.