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Stair Calculator

Enter your total rise (floor-to-floor height) to get the number of steps, the exact riser height, and the tread depth — with an automatic check against IRC limits of a 7¾-inch maximum riser and 10-inch minimum tread.

Meets IRC riser and tread limits.
You need approximately
15 steps
7.2" riser · 10.5" tread
Riser height
7.2 in
Number of treads
14
Total run
147 in

Field notes

Consistency is a safety issue, not a nicety — the code limits the variation between the tallest and shortest riser in a flight to ⅜ inch, because an uneven step is exactly where people trip. Size the whole flight from the total floor-to-floor rise, divide into equal risers near 7 inches, and never fudge the last step to make the math close. Measure the rise in three spots; floors are rarely level.

How the stair calculator works

The math behind the tool:

steps = round(total rise ÷ 7)
riser = total rise ÷ steps

Sources: International Code Council (IRC) (residential stair riser/tread code limits).

Frequently asked questions

How do you calculate stair rise and run?

Divide the total floor-to-floor rise by a target riser near 7 inches and round to a whole number of steps, then divide the total rise by that step count for the exact riser height. Treads are typically 10–11 inches deep.

What is the maximum riser height by code?

The International Residential Code sets a maximum riser height of 7¾ inches and a minimum tread depth of 10 inches for residential stairs.

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