Use this guide to determine the angle of your stairs. If using angle washers, choose the angle washer with the angle that most closely matches your stairs.

Stair Angle Guide
Stair Tread Width Stair Riser Height Angle or Slope
12-1/2" 5" 22 degrees
12/1-4" 5-1/4" 23 degrees
12" 5-1/2" 24 degrees
11-3/4" 5-3/4" 26 degrees
11-1/2" 6" 27 degrees
11-1/4" 6-1/4" 29 degrees
11" 6-1/2" 30 degrees
10-3/4" 6-3/4" 32 degrees
10-1/2" 7" 33 degrees
10-1/4" 7-1/4" 35 degrees
10" 7-1/2" 36 degrees
9-3/4" 7-3/4" 38 degrees
9-1/2" 8" 40 degrees