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Stair Tread Count Calculator

Enter the total rise and ideal riser height to count your stair risers and treads.

How it is calculated

Both numbers are in inches: the total rise from finished floor to finished floor, and the riser height you would like. risers = round(total rise / ideal riser), rounded to the nearest whole number with a minimum of 1. actual riser = total rise / risers, shown in inches to two decimals, so the flight divides evenly. treads = risers − 1, because the top riser lands on the upper floor, not on a tread. The tool rounds to the nearest count, so the actual riser can end up a little above or below your ideal. It checks nothing against a building code, and it does not work out tread depth, run, headroom or stringer length.

Worked example

A total rise of 106 inches and an ideal riser of 7.25 inches. 106 / 7.25 = 14.62, which rounds to 15 risers. The actual riser is 106 / 15 = 7.07 inches. The number of treads is 15 − 1 = 14. The tool shows 15 risers, 14 treads and an actual riser of 7.07 in. All 15 risers are the same height, a little under the 7.25 you asked for, because the count was rounded up.

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Common mistakes

  • Entering centimetres. The fields are inches, and a 274 cm rise typed as 274 with an 18 cm riser gives 15 risers of 18.27 in, which is nonsense. Divide cm by 2.54 first.
  • Measuring the total rise from the rough subfloor instead of finished floor to finished floor. A flooring layer at the top or bottom changes the rise and makes the first or last step uneven.
  • Counting the top floor as a tread. The number of treads is one less than the risers, so 15 risers means 14 treads to cut.
  • Accepting the rounded riser without checking local code. The tool may round to a riser above your maximum, so check that the actual riser fits the limit for your area.
  • Using the result to set tread depth. The tool gives counts and riser height only; the going of each tread comes from your design and the code.

About this calculator

Building a staircase starts with dividing the total rise (floor-to-floor height) into individual risers — the vertical part of each step — close to a comfortable target height, typically 7 to 7.75 inches (175–200mm) under most residential building codes. This calculator divides total rise by your ideal riser height (both entered in inches), rounds to a whole number of risers, and recalculates the exact riser height, in inches, that comes out even.

The number of treads (the horizontal part you step on) is always one less than the number of risers, since the top riser lands you on the upper floor itself rather than another tread. A staircase with a 108-inch total rise and a 7.2-inch target riser needs 15 risers (108 ÷ 7.2 = 15) and 14 treads.

DIYers, carpenters, and contractors use this early in framing a staircase to lock in consistent riser heights — code typically requires each riser in a flight to be within about 3/8 inch of the others, since uneven steps are a common trip hazard.

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  • Editorial team

    The tool gives counts, not floor space. To estimate the horizontal run, multiply the tread count by the tread depth you choose: 14 treads of 10 inches need 140 inches, about 11.7 feet, of floor length before landings. Pick the tread depth from your own design and local rules. Is your stair limited more by length or by headroom?

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