Stairs should be installed between 30 and 50 degrees from the horizontal, according to widely used safety and building standards.

Standard stair angle

  • Workplace and industrial safety regulations specify that stairways must be set at an angle between 30° and 50° from the horizontal.
  • This range balances safe footing, comfortable use, and efficient use of space in most buildings.

Common practice within the range

  • Many residential and commercial interior stairs are often built in the narrower range of about 30°–37° for everyday comfort.
  • Specialized stairs (such as very steep or ship-style stairs) may approach the upper end of the allowed 30°–50° range and feel noticeably steeper.

Answer to fill-in-the-blank:
Stairs should be installed between 30 and 50 degrees from horizontal.

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