Stair Calculator
Enter the total rise to lay out a comfortable staircase — steps, riser height, tread depth, run, and stringer length.
Results are estimates for planning. Stair dimensions are tightly regulated — always confirm riser, tread, and headroom against your local building code before building.
How to Lay Out a Staircase
A staircase is designed from the total rise — the finished-floor to finished-floor height the stairs must climb.
Total rise
Measure the vertical distance from the lower finished floor to the upper finished floor in inches. The calculator splits it into equal risers near 7.5 inches.
Tread depth
The tread depth — the run — is how deep each step is front to back. Ten to eleven inches is typical. The total run tells you the horizontal space the stairs need.
Common Mistakes to Avoid
- Unequal risers. Every riser in a flight must be the same height — uneven steps are a trip hazard and fail inspection.
- Forgetting tread overhang. Treads usually overhang the riser by about an inch; the run and tread depth are not always identical.
- Ignoring headroom. Check there is enough clearance above the stairs, not just floor space for the run.
- No allowance on the stringer. Cut stringers slightly long — you can trim, but you can't add material back.
Frequently Asked Questions
Divide the total rise by a comfortable riser of about 7.5 inches and round to a whole number — that's the number of steps.
Around 7-7.5 inches, with most codes capping it near 7.75 inches. Every riser in a flight should be equal.
Rise is the vertical height of a step; run (tread depth) is the horizontal depth you step on.
Twice the riser plus the tread depth should be about 24-25 inches — a classic test for comfortable stairs.
It's the diagonal — the square root of total rise squared plus total run squared. Add length for end cuts.