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Stair Calculator

Riser, slope angle and run from height, steps and tread

Stair Dimensions
Riser (R)
0 mm
Details
⚠️ This calculator is a simple reference tool based on standard engineering formulas. Actual required values may differ due to site conditions, materials, construction tolerances, specifications and changes in applicable regulations. calcstool.com assumes no legal liability for any decisions or damages arising from use of these results.
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FAQ
How is riser height calculated?
Riser (R) = total height ÷ number of steps. For a 2800 mm floor height with 15 steps, the riser is about 187 mm.
What makes a comfortable stair?
By the walking formula, 2R+T (twice riser plus tread) of about 600–640 mm is comfortable. Homes typically use 150–200 mm risers and 250–300 mm treads.
How is the slope angle found?
Slope = arctan(riser ÷ tread). Around 30–35° is typical for interior stairs.
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Stair Calculation

Comfortable stairs depend on the balance of riser (R) and tread (T). Dividing the floor height by the number of steps gives the riser; with the tread you can check slope and the 2R+T comfort rule.

Method

Riser = height ÷ steps, slope = arctan(riser ÷ tread). The walking formula 2R+T is recommended in the 600–640 mm range.

Typical values

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