Concrete & construction
Concrete Stair Calculator
Works stair concrete, where the rise and run are governed before the volume.
Result
Rise and run are set by code, not by preference: most jurisdictions cap the rise around 7.75 inches and require a minimum tread, and every step in a flight has to match within a small tolerance. Check yours before forming anything.
Get a Free Business AuditHow the calculation works
The volume of the stair mass, calculated as the triangular section of the steps plus the slab beneath, times the width. The rise and run dimensions come from the code, which sets maximum rise, minimum run and the uniformity required between steps.
What moves the number
- Number of risers and the total height.
- Rise and run within the code's limits.
- Width and the thickness of the supporting slab.
- Landing and footing requirements.
Where this one goes wrong
Rise and run are code-controlled and the uniformity requirement is strict, because an uneven step is a trip hazard and inconsistency between steps is what causes falls, which means dividing the total height into equal risers is the first calculation rather than an adjustment. Set out from the total height. Formwork for stairs is also disproportionately involved relative to the concrete volume, which makes the labour rather than the material the cost.
Before you quote
- Divide the total height into equal risers first.
- Check rise and run against the adopted code limits.
- Expect formwork labour to exceed the material cost.
Where the rules come from
Questions
About this calculator
How do I set out concrete stairs?
From the total height, divided into equal risers within the code's maximum. Uniformity between steps is a strict requirement because inconsistency causes falls, which makes the division the first calculation rather than something adjusted at the end.
Are rise and run regulated?
Yes, with a maximum rise, a minimum run and a uniformity tolerance set by the adopted code. They are requirements rather than guidance, and an inspection will check them, so they constrain the design before the volume is calculated.
Why are concrete stairs expensive?
Formwork. The forms for stairs are disproportionately involved relative to the modest concrete volume, which makes labour rather than material the cost, and it is why stair formwork is usually the longest part of the job.
The formula
volume = sum of each step's wedge + the slab beneath, converted to cubic yards
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How to use this calculator
- Number of steps. Enter your own figure; the page starts at 5.
- Rise per step (in) (in). Enter your own figure; the page starts at 7.5 in.
- Tread depth (in) (in). Enter your own figure; the page starts at 11 in.
- Stair width (ft) (ft). Enter your own figure; the page starts at 4 ft.
- Slab thickness under the steps (in) (in). Enter your own figure; the page starts at 6 in.
- Concrete per cubic yard ($). Enter your own figure; the page starts at $165.
The result updates as you type, so you can try a figure, see what it does to cubic yards to order, and change it back. Nothing you enter is sent anywhere or saved.
A worked example
These are the figures the calculator opens with. Every number in the results column below is produced by the same calculation the page runs, so you can follow it through before putting your own figures in.
What goes in
| Input | Value |
|---|---|
| Number of steps | 5 |
| Rise per step (in) | 7.5 in |
| Tread depth (in) | 11 in |
| Stair width (ft) | 4 ft |
| Slab thickness under the steps (in) | 6 in |
| Concrete per cubic yard | $165 |
What comes out
| Result | Value |
|---|---|
| Cubic yards to order main result | 2.0 |
| Volume | 43.5 |
| Total rise | 37.5 |
| Total run | 55.0 |
| Estimated concrete cost | $330 |
5 steps rising 37.5 inches take 2.0 cubic yards, about $330 of concrete.
How sensitive the answer is
Holding everything else steady and changing only concrete per cubic yard, this is what happens to cubic yards to order. It is worth knowing which of your inputs the answer actually hinges on, and which barely move it.
| Concrete per cubic yard ($) | Cubic yards to order |
|---|---|
| $83 | 2.0 |
| $124 | 2.0 |
| $165 example above | 2.0 |
| $248 | 2.0 |
| $330 | 2.0 |
Every other input is held at the example value while this one changes, which is not how a real job behaves. Treat it as a guide to which number matters most, not as five separate quotes.
What each figure means
- Number of steps
- A number, between 0 and 60, starting at 5.
- Rise per step (in) (in)
- Measured in in, between 0 and 12, starting at 7.5 in.
- Tread depth (in) (in)
- Measured in in, between 0 and 24, starting at 11 in.
- Stair width (ft) (ft)
- Measured in ft, starting at 4 ft.
- Slab thickness under the steps (in) (in)
- Measured in in, between 0 and 24, starting at 6 in.
- Concrete per cubic yard ($)
- A money amount, starting at $165.
What the results tell you
| Result | What it is |
|---|---|
| Cubic yards to order | The headline result. A decimal figure. |
| Volume | A decimal figure. |
| Total rise | A decimal figure. |
| Total run | A decimal figure. |
| Estimated concrete cost | A money figure. |
Order slightly more than this
Volume calculations assume a level, properly prepared base and exact dimensions. Sub-base variation, over-excavation and spillage all consume concrete, which is why most contractors add a margin. Running short mid-pour is far more expensive than a small overage.
Keep going
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