About this calculator

How-to: enter total floor-to-floor height and target riser height (170–200 mm domestic UK/EU; 178 mm US IRC). We compute the riser count that gives the closest legal rise, then apply the rule 2R + T ≈ 600–640 mm to derive tread depth. Angle = atan(rise ÷ tread). Total run = tread × (risers − 1).

Frequently asked questions

What's the UK/EU rule of thumb for comfort?

2R + T should sit between 600 and 640 mm, and R + T between 430 and 460 mm. This calculator uses 620 mm as the auto tread target.

Can I have unequal risers?

No — all risers on a flight must be equal within ±5 mm to avoid a trip hazard. Adjust the total height or add a landing to hit a whole-number riser count.

What about winder or spiral stairs?

Winders and spirals follow separate geometry rules (min tread at 270 mm from the inside edge). This calculator is for straight or half-landing flights.

What does the Staircase Rise & Run Calculator do?

Number of risers, tread depth, stair angle and total run for a stair that fits your floor-to-floor height, checked against UK Part K / IRC codes. How-to: enter total floor-to-floor height and target riser height (170–200 mm domestic UK/EU; 178 mm US IRC). We compute the riser count that gives the closest legal rise, then apply the rule 2R + T ≈ 600–640 mm to derive tread depth. Angle = atan(rise ÷ tread). Total run = tread × (risers − 1).

Is the Staircase Rise & Run Calculator free to use?

Yes. Every calculator on Calcurly.com is free, works in your browser without sign-up, and can be embedded on your own website.

How accurate is the Staircase Rise & Run Calculator?

Results are calculated in real time using industry-standard formulas. Treat the output as a well-informed estimate — always cross-check with local regulations, product datasheets, or a qualified construction & building professional before committing to a purchase or a job.

What inputs does the Staircase Rise & Run Calculator need?

Enter values for: Floor-to-floor height (mm), Target riser (mm), Tread going (mm, 0 = auto), Stair width (mm). Sensible defaults are pre-filled where possible so you can start with a single change.

Can I embed the Staircase Rise & Run Calculator on my own website?

Yes — copy the iframe snippet at the bottom of this page, or use the Embed Generator to customise the size. The embedded version stays in sync with the live calculator on Calcurly.com.