Staircase Calculator
Free staircase calculator: enter your total floor-to-floor rise to get the number of steps, exact riser height, tread count and total run, with a comfort check.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Show the formula & steps
How the Staircase Calculator Works
This calculator turns a single measurement — the total rise (floor-to-floor height) — into a complete stair layout. Enter your rise, a target riser height, and your planned tread depth, and it returns the number of steps, the exact riser height, the number of treads, and the total horizontal run. It also runs a comfort check so your stairs feel safe to climb.
The Formula
A staircase is built from risers (the vertical face of each step) and treads (the flat part you step on). The math is straightforward:
Number of risers = round(total rise ÷ target riser height) Actual riser height = total rise ÷ number of risers Number of treads = number of risers − 1 Total run = number of treads × tread depth
Because the upper floor itself serves as the last step, there is always one fewer tread than riser. The actual riser height rarely equals your target exactly — rounding to a whole number of steps adjusts it slightly so every step is identical.
Worked Example
Suppose your total rise is 110 in, your target riser is 7.5 in, and your tread depth is 10 in:
- Risers = round(110 ÷ 7.5) = round(14.67) = 15 risers
- Actual riser height = 110 ÷ 15 = 7.33 in
- Treads = 15 − 1 = 14 treads
- Total run = 14 × 10 = 140 in
Check the comfort rule: 2 × 7.33 + 10 = 24.67 in, comfortably inside the 24–25 in target range.
Comfort and Code Rules
Three quick checks keep a staircase safe and easy to climb:
- Riser height should not exceed roughly 7.75 in in most residential codes.
- Tread depth should be at least 10 in so your foot lands fully.
- The 2R + T rule (2 × riser + tread) should land between 24 and 25 in.
If the actual riser height comes out too tall, add a step; if it is unusually short, remove one. Always confirm the exact figures against your local building code before cutting stringers.
| Total rise | Risers | Riser height | Treads | Total run (10 in tread) |
|---|---|---|---|---|
| 96 in | 13 | 7.38 in | 12 | 120 in |
| 110 in | 15 | 7.33 in | 14 | 140 in |
| 120 in | 16 | 7.50 in | 15 | 150 in |
Frequently asked questions
How do I calculate the number of steps in a staircase?+
Divide the total floor-to-floor rise by your target riser height and round to the nearest whole number. For a 110 in rise and a 7.5 in target riser, 110 ÷ 7.5 = 14.67, which rounds to 15 risers. The actual riser height then becomes 110 ÷ 15 = 7.33 in.
What is the ideal riser height and tread depth?+
Most residential codes cap risers at about 7.75 in and require treads of at least 10 in. A comfortable stair follows the rule 2 × riser + tread = 24 to 25 in, so a 7 in riser pairs well with a 10 to 11 in tread.
Why is the number of treads one less than the number of risers?+
The top landing or floor acts as the final 'step,' so a staircase always has one fewer tread than risers. If you have 15 risers, you walk on 14 treads before reaching the upper floor.
How do I find the total run of a staircase?+
Multiply the number of treads by the tread depth (the horizontal going of each step). With 14 treads at 10 in each, the total horizontal run is 14 × 10 = 140 in, which is the floor space the stair occupies.
What is the 2R plus T rule for stairs?+
The 2R + T comfort rule states that twice the riser height plus the tread depth should equal 24 to 25 in. It keeps the stride natural so the staircase feels neither too steep nor too shallow to climb.