A 2.7 m floor-to-floor rise
15 risers of 180 mm and 14 treads of 270 mm: a total run of 3,780 mm and 2R + T = 630 mm.
Stair Calculator
Plan straight stairs: number of steps, riser height, treads, total run and stringer length.
Result
Enter your values and select Calculate to see the result.
Result
Enter your values and select Calculate to see the result.
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How the Stair Calculator works
Measure the total rise from finished floor to finished floor. The calculator divides it into the fewest equal risers that stay under your maximum riser height, then works out the treads, total run, stringer length and angle, and checks the comfort rule and the US IRC limits for homes.
Formulas
Risers
risers = ⌈total rise ÷ maximum riser⌉, riser height = total rise ÷ risers
Run
treads = risers − 1, total run = treads × tread depth
Comfort
2 × riser + tread ≈ 600–650 mm (24–25½ in)
Examples
US limits
The IRC allows risers up to 7¾ in and requires treads of at least 10 in for homes.
Frequently asked questions
Why is there one fewer tread than risers?
The top step is the upper floor itself.
What about headroom?
Most codes require about 2 m (6 ft 8 in) of headroom above the stair line — check yours.
Do I need a handrail?
Usually yes once there are more than a few risers; codes set the height and grip size.
Information:
Good to know
Estimates for planning. Follow local building codes and the manufacturer's instructions, and use a qualified professional for structural or electrical work.
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