Round Slab Concrete Calculator
Estimate concrete volume for a measured circular slab from its diameter and thickness, with a user-chosen extra-volume allowance.
Reference calculation or estimate for example inputs; assumptions and limitations apply.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Internal diameter (m) | Enter internal diameter in m; use the same basis as the other measurements. |
| Height or depth (m) | Enter height or depth in m; use the same basis as the other measurements. |
| Extra volume allowance (%) | Enter percentage units: 5 means 5%, not a fraction of 0.05. |
Understanding your result
The answer estimates quantity, coverage or cost from the dimensions and allowances you entered. It does not size a structural member, assess capacity or determine installation adequacy.
Common mistakes
- Mixing centimetres with metres, or outside dimensions with the actual filled volume.
- Treating allowance, compaction, supplier yield and density as interchangeable adjustments.
Check your calculation
- Measure independently, subdivide irregular shapes, and compare supplier pack/yield information with the units used here.
Calculation checks, sources and review limits
How much concrete fills a circular slab of my measured diameter and thickness?
Estimate concrete volume for a measured circular slab from its diameter and thickness, with a user-chosen extra-volume allowance.
Common uses
- How much concrete fills a circular slab of my measured diameter and thickness
- Check cylinder volume and volume with allowance using the actual inputs shown.
How it works
Halve the measured diameter to obtain the radius, square it, multiply by pi, then multiply by measured slab thickness in the same length unit. This calculates a solid circular-cylinder volume. The extra-volume percentage scales that geometric volume; it does not change the measured dimensions or determine slab thickness, reinforcement, bearing capacity or structural design.
Worked example
Enter Internal diameter: 2 m; Height or depth: 1 m; Extra volume allowance: 0 %. Results: Cylinder volume: 3.141592653589793 m³; Volume with allowance: 3.141592653589793 m³.