Concrete Calculator
Calculate the concrete needed for slabs, footings, columns and steps, plus bags required.
Enter your values to see the result.
Estimates only. Measure carefully and check quantities with your supplier before ordering.
Continue your work
- Cement Calculator — Mix concrete yourself from cement, sand and gravel.
- Cubic Yard Calculator — Convert other volumes to cubic yards.
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Clear instructions
Find steps, examples and limitations below.
Use online
Open the tool in a supported web browser.
Free to use
No sign-up required. Tool-specific limits may apply.
How to use the Concrete Calculator
Calculate the concrete needed for slabs, footings, columns and steps, plus bags required.
- 1 Choose units and the type of project.
- 2 Enter the dimensions and how many you are pouring.
- 3 Read the volume and the number of 40, 60, 80 lb or 25 kg bags.
Example and practical tips
A 10 × 10 ft patio slab 4 in thick needs about 1.36 cubic yards with 10% waste, which is about 61 bags of 80 lb premix.
Frequently asked questions
Bags or ready-mix truck?
Bags suit small jobs under about 1 cubic yard. For larger pours, ready-mix is usually cheaper and faster.
How much extra should I order?
Add 5–10% for spillage, uneven ground and forms that bow.
Report an issue
Something broken or not quite right? Tell us and we will look into it.