Standard Stair Dimensions by Country (US, UK, EU & ISO)
Quick reference for riser heights, tread depths, stair angles and ergonomic rules used across major building codes.
Why stair standards vary
Different regions interpret comfort, space constraints and safety in slightly different ways. The result is small variations in riser heights, tread depths and acceptable angles — but the overall logic is almost the same everywhere.
Universal principles across most regions
- Max riser height usually 180–200 mm.
- Min tread depth typically 230–250 mm.
- Consistency required within 5–10 mm.
- Comfortable stair angle is typically 30°–37°.
- Ergonomic guideline:
2 × rise + run ≈ 600–640 mm.
Test proportions using the Stair Calculator.
United States — IRC & IBC
Residential (IRC)
- Max riser: ~196 mm
- Min tread: ~254 mm
- Variation limit: ≤ 10 mm
Commercial (IBC)
- Max riser: ~180 mm
- Min tread: ~280 mm
United Kingdom
Private residential
- Riser: 150–190 mm
- Tread: 220–280 mm
Public / institutional
Public stairs must be shallower for accessibility and safety.
European / ISO
- Riser: 150–180 mm
- Tread: 250–300 mm
- Ergonomics:
2 × rise + run ≈ 600–640 mm - Angle: 30°–37°
Australia / New Zealand
- Riser: 130–225 mm
- Tread: 215–355 mm
- Pitch: max up to ~45° in certain cases
Stair angle comparison
| Region | Comfortable angle | Common max |
|---|---|---|
| United States | 30°–37° | 40°–42° |
| United Kingdom | 30°–37° | 42° |
| Europe / ISO | 30°–37° | ~40° |
| Australia / NZ | 30°–38° | ~45° |
Recommended safe geometry
- Rise: 150–180 mm
- Run: 250–300 mm
- Angle: 30°–37°
- Use ergonomic formula for checking balance.
Verify your design
Use the Stair Calculator to compare options and optimise comfort and compliance.