Stair Riser Height Calculator
This free stair riser height calculator turns your total rise into evenly spaced steps. Enter the total rise and your target riser height — it instantly computes how many risers you need, the exact height of each riser, the tread count and depth, and warns you if the result falls outside the typical 4"–7.75" code range.
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Enter your total rise to see the step layout.
How to use this calculator
Measure the total rise — the vertical distance from the finished surface of the lower floor to the finished surface of the upper floor, in inches. Include any finished flooring on both levels; a new tile floor at the bottom or a thicker subfloor at the top changes the number.
Pick your target riser height (7" is the common default) and read the results: the number of risers, the exact riser height (the total rise divided evenly), the tread count and an estimated tread depth, plus the stair's total horizontal run. If the riser falls outside the typical 4"–7.75" code range, you'll get a warning. Results update instantly as you type.
How it works
The riser count is found by dividing the total rise by your target riser height and rounding to the nearest whole number — then the exact riser height is simply the total rise split evenly across that count:
risers = round(total rise ÷ target riser height)
exact riser height = total rise ÷ risers
For example, a 105" rise with a 7" target gives round(105 ÷ 7) = 15 risers, each exactly 105 ÷ 15 = 7.0" tall. A 100" rise gives round(100 ÷ 7) = round(14.29) = 14 risers, each exactly 100 ÷ 14 = 7.14" tall.
There is always one fewer tread than risers, because the upper floor or landing serves as the final step. The suggested tread depth comes from the classic comfort rule 2 × riser + tread ≈ 25" (an estimate, not a code rule), and the total run is the tread depth times the tread count. If your target is larger than the total rise, the count clamps to 1 riser and the riser height equals the total rise.
Code values mentioned here (e.g. the 4"–7.75" range and 10" minimum tread depth under the IRC) are general guidance only, not legal advice. Actual requirements vary by jurisdiction, so confirm your stair design with your local building code and inspector before you build.
Frequently asked questions
How do you calculate stair riser height?
Divide the total rise (the vertical distance from the lower floor to the upper floor) by the number of risers, and you get the exact riser height. The number of risers comes from dividing the total rise by your target riser height and rounding to the nearest whole number. For example, a 105 in total rise with a 7 in target gives round(105 / 7) = 15 risers, so each riser is exactly 105 / 15 = 7.0 in tall. The calculator above does this instantly.
What is the standard stair riser height?
A 7 in riser is the most common target for residential stairs. As general guidance, the International Residential Code (IRC) allows a maximum riser height of 7.75 in, with most codes expecting risers between 4 in and 7.75 in and all risers in a flight within 3/8 in of each other. These values are guidance only, not legal advice — check your local building code and inspector before you build.
How many treads do I need for my stairs?
You need one fewer tread than risers, because the upper floor or landing counts as the last step. A 15-riser stair has 14 treads. The calculator shows your tread count automatically along with an estimated tread depth and the total horizontal run of the stair.
What tread depth goes with my riser height?
A widely used comfort rule is that two risers plus one tread should add up to about 24 to 26 in (often quoted as 25 in). So for a 7 in riser, aim for a tread depth around 11 in. As general guidance, the IRC requires a minimum tread depth of 10 in. The calculator applies the 25 in rule to suggest a tread depth for your exact riser height.
What if my total rise is smaller than the target riser height?
Then you get a single riser: the calculator clamps the count to at least 1, and the actual riser height simply equals your total rise. Single steps can be a trip hazard, and some codes have minimum riser rules, so check your local building code before building one.