Stair Calculator
The Stair Calculator determines how many risers and treads you need based on total rise, keeping each riser height within a comfortable, code-friendly range. Enter measurements in inches or centimeters. Because the riser count comes from rounding total rise ÷ target riser to the nearest whole number, the actual riser height that comes back can land slightly above or below your target — entering a target already near the edge of your code's allowed range (7.75 inches, for example) can push the rounded, real-world result outside that range, so it's safer to aim for the middle of the allowed band. Total run is calculated from tread run alone and does not add any nosing overhang, so if your finished treads project past the riser below them (typical nosing is 3/4 to 1-1/4 inch), add that separately when checking the stair's footprint against available floor space.
Switch between U.S. Customary and Metric units.
How This Tool Works
Pick your units, then enter the total vertical rise (floor to floor height) and your target riser height to calculate the exact number of risers and treads needed.
Formula & Method
Number of risers = total rise ÷ target riser height (rounded to nearest whole number). Actual riser height = total rise ÷ number of risers. Treads = risers − 1. Enter rise and target dimensions in inches or centimeters.
Example Calculation
A staircase with 100 inches of total rise, targeting 7 inch risers and an 11 inch tread run: number of risers = round(100 ÷ 7) = round(14.29) = 14. Actual riser height = 100 ÷ 14 = 7.14 inches. Treads = 14 − 1 = 13. Total run = 13 × 11 = 143 inches (11.92 ft). In metric, 254 cm of rise (equal to 100 inches) targeting 18 cm risers and a 28 cm tread run also gives 14 risers, at an actual height of about 18.1 cm each, with 13 treads and a total run of 364.0 cm (3.64 m).
Frequently Asked Questions
What is a comfortable riser height?+
Most building codes require risers between 7 and 7.75 inches (about 18–19.5 cm). The calculator adjusts your target evenly across all risers so every step is the same height.
Can I plan stairs in centimeters?+
Yes — switch the unit toggle to Metric and enter the total rise and target riser and tread in centimeters. Riser height and total run are returned in centimeters and meters.
Why is even riser height important?+
Uneven risers are a major trip hazard — even a 3/8 inch (about 1 cm) difference between steps can throw off a person's stride and cause falls.
Should I check local building codes?+
Yes, always confirm your local code requirements for riser height, tread depth, and handrail specifications before building or modifying stairs.
Why didn't I get exactly my target riser height back?+
The calculator always uses a whole number of risers, so it rounds total rise ÷ target riser to the nearest whole riser, then spreads the full rise evenly across that many risers. If your total rise doesn't divide evenly by your target, the real riser height comes back a bit taller or shorter than what you typed — that's expected and matches how a real staircase gets laid out.
Does total run include the tread nosing overhang?+
No — total run is simply the number of treads (one fewer than the number of risers) multiplied by your target tread run, measuring only the flat run dimension. Most finished treads also have a nosing that overhangs the riser below by about 3/4 to 1-1/4 inch, which adds a small amount to how far the staircase actually projects but isn't included in this total.
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<a href="https://everyfix.net/tools/stair-calculator/">Stair Calculator</a> by <a href="https://everyfix.net">EveryFix</a>Related Tools
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