Stair Calculator

How it works

Enter the height from finished floor to finished floor, your preferred step height and the tread depth. The calculator rounds to a whole number of steps, works out the exact step height, the horizontal length of the stairs, the angle and the stringer length. For comfortable stairs, the step rule 2 × height + depth should be about 63 cm (60–65 cm), with steps around 16–19 cm high. Always check local building regulations.

Formula

n = round(H / h_target)    h = H / n
run = (n − 1) × b    angle = atan(h / b)
step rule: 2h + b ≈ 63 cm (60–65 cm)

Worked examples

• Floor-to-floor height (cm): 260 · Desired step height (cm): 17.5 · Tread depth (cm): 28 → Number of steps (risers): 15
• Floor-to-floor height (cm): 300 · Desired step height (cm): 18 · Tread depth (cm): 26 → Number of steps (risers): 17
• Floor-to-floor height (cm): 250 · Desired step height (cm): 17 · Tread depth (cm): 29 → Number of steps (risers): 15

Calculations run locally in your browser. Results are for information only — for engineering, electrical or financial decisions, verify the assumptions and applicable standards.