FIELD GEOMETRY / FREE CALCULATOR

Stair rise and run calculator

Start with the finished-floor-to-finished-floor rise, your target riser height and tread depth. This calculator divides the rise equally and estimates a straight flight with the upper floor as its final landing.

Worked example: a 108-inch floor-to-floor rise

1. Choose a target riser height of 7.5 inches: 108 ÷ 7.5 = 14.4.
2. Round the count up to 15 risers.
3. Divide the rise equally: 108 ÷ 15 = 7.2 inches per riser.
4. With the upper floor as the landing, there are 14 treads.
5. At a 10-inch tread depth, the horizontal run is 14 × 10 = 140 inches.

Why the riser count is rounded up

Rounding up keeps the calculated equal riser height at or below your entered target. The target is your input, not a legal maximum. Confirm the permitted dimensions for the project before choosing it.

Why there is one fewer tread than riser

The model assumes you step onto the upper floor after the final rise. It counts the treads below that landing. A different landing arrangement, multiple flights, winders or spiral stairs needs a different layout.

Check more than the rise and run

The calculation omits nosing, landings, headroom, guards, handrails, finish thickness and structural details. Measure between finished floor levels, allow for the actual construction and verify the complete design. These results do not certify a staircase or its compliance.

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Original calculator by Eutopix Labs · Published 15 September 2026.