How to use it
A better estimate in three steps.
- 01
Measure the slab length, width, and finished depth.
- 02
Add waste for uneven subgrade, spillage, and form variation.
- 03
Use your bag's stated yield for the closest estimate.
Home & DIY
Concrete Calculator
Calculate slab volume, order volume, ready-mix quantity, bag count, and budget in metric or US customary units.
01
Enter your details
Results update instantly as you type.
Core formula
The math behind the result.
Concrete volume = length × width × depth; order volume = volume × (1 + waste rate)Questions
Useful before you decide.
How much extra concrete is sensible?
For a regular slab, 5–10% is common. Irregular excavation or uncertain depth can require more.
Why does bag yield matter?
Bag weight alone does not guarantee the same mixed volume. Use the yield printed by the manufacturer.
Can I use this for structural work?
Use it for preliminary quantity planning only. Structural dimensions and mix specifications should come from the project design and local requirements.