Stair Tread Count Calculator

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, rounds to a whole number of risers, and recalculates the exact riser height 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.