Stair Calculator

Your details

The vertical distance from the surface of the lower floor to the surface of the upper floor.
in
Either aim for a comfortable riser height, or fix the step count and let the riser follow.
A comfortable riser is about 7 in (178 mm). Many codes cap risers at 7.75 in (196 mm).
in
The horizontal depth of each step. A minimum of 10 in (254 mm) is typical.
in
A standard mount has one fewer tread than risers; a flush mount keeps a full tread at the top.
Check the headroom under a floor opening above the stairs.
Currency
Number of steps (risers)Comfortable stair angle
16
Actual riser height7 in
Number of treads15
Total run (horizontal)165 in
Stringer length199.42 in
Stringer height (vertical)112 in
Stair angle34.2deg
2 x riser + tread (comfort)25 in
34.2 deg
Shallow<20Easy20-30Comfortable30-37Steep37-42Very steep42+

You need 16 steps with a 7 in riser and a 165 in total run.

  • The total rise is split into 16 equal risers; with a standard mount that gives 15 treads and a 165 in total run.
  • Two risers plus one tread (2R + T) is about 25 in; the comfort sweet spot is 24-25 in, so adjust the tread or riser if you fall outside it.
  • The stringer board must be at least 199.42 in long, set at about 34.2 degrees, to span the rise and run; add length for the top and bottom connections.

Next stepCheck the riser, tread, angle and headroom against your local building code before cutting the stringers.

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