Stair Tread & Riser Calculator â How Many Steps Do I Need?
Enter your floor-to-floor height to get the number of risers, treads, and the total horizontal run of your stairs. No sign-up, no data stored.
Stairs needed
How stairs are calculated
- Risers = total rise (floor-to-floor height) ÷ riser height, rounded up.
- Treads = risers â 1 (the floor landing is the final step).
- Total run = treads à tread depth (nosing does not add to the structural run, only to the visual overhang).
- Code check: keep risers between 7 and 7.75 in and treads at least 10 in deep, with every riser within 3/16 in of each other in one flight.
If the exact riser height from the division lands outside 7â7.75 in, adjust the number of risers by one and recompute â the actual riser height is the total rise divided by the number of risers you choose.
Stair counts by floor height
Typical counts for common floor-to-floor heights using 7-in risers and 10-in treads.
| Floor height | Risers | Treads | Total run |
|---|---|---|---|
| 8 ft (96 in) | 14 | 13 | 10.8 ft |
| 9 ft (108 in) | 16 | 15 | 12.5 ft |
| 10 ft (120 in) | 18 | 17 | 14.2 ft |
| 11 ft (132 in) | 19 | 18 | 15 ft |
Last updated: October 2026 · Estimates use 7-in risers and 10-in treads, the common residential target. Verify local building codes before building.
Stair calculator FAQ
About 18 risers and 17 treads â a 120-in floor-to-floor height divided by 7-in risers is 17.1, rounded up to 18. The run is roughly 14.2 ft at 10-in treads.
7.75 inches in most US codes (IRC), with a minimum of about 4 in. The minimum tread depth is usually 10 inches, measured nose to nose.
A straight stair for a 9-ft ceiling needs about 12.5 ft of run plus a top and bottom landing. Turned stairs (L or U shape) cut the straight run in half or more.
Yes â the landing counts as the final step, which is why you subtract one from the riser count to get treads. Most DIY mistakes come from counting both the top and bottom landings.
Round to a whole number of risers first, then divide the total rise by that number to get the exact riser height. Keep every riser within 3/16 in of each other or the stairs fail code and feel unsafe.
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