Stair Rise Calc
Answer The limits every stairway has to meet, and where each one comes from.

Standard stair dimensions

Riser height, maximum
73/4inIRC 2021 (residential)
Tread depth, minimum
10inIRC 2021 (residential)
Headroom, minimum
80inIRC 2021 (residential)
Riser height, maximum
7inADA 2010
Tread depth, minimum
11inADA 2010
The envelope a stairway has to sit inside, drawn where each limit is taken: the tallest riser and the shallowest tread on the step itself, the riser variation beside it, the least headroom over it and the least width across it. Each label names the code that sets the figure, and the table below carries all 12 limits of both codes with their sections. Riser, maximum7 inADA Riser variation3⁄8 inIRC Tread, minimum11 inADA Headroom, least80 inIRC Width, least36 inIRC
Limits

Every limit, with the code it comes from

Dimension Value Code Applies to
Riser height, maximum 73/4in7 3/4 in IRC 2021 (residential) Homes
Tread depth, minimum 10in10 in IRC 2021 (residential) Homes
Headroom, minimum 80in6 ft 8 in IRC 2021 (residential) Homes
Stair width, minimum 36in36 in IRC 2021 (residential) Homes
Riser variation, maximum 3/8in3/8 in IRC 2021 (residential) Homes
Tread variation, maximum 3/8in3/8 in IRC 2021 (residential) Homes
Landing length, minimum 36in36 in IRC 2021 (residential) Homes
Riser height, minimum 4in4 in ADA 2010504.2 Accessible route
Riser height, maximum 7in7 in ADA 2010504.2 Accessible route
Tread depth, minimum 11in11 in ADA 2010504.2 Accessible route
Nosing radius, maximum 1/2in1/2 in ADA 2010504.5 Accessible route
Nosing projection, maximum 11/2in1 1/2 in ADA 2010504.5 Accessible route
Comfort

Rise and run pairs that satisfy both

Pairs that sit inside both codes.
Riser Tread 2R + T Angle Result
61/2in 11in 24in 30.6° Within
61/2in 111/2in 241/2in 29.5° Within
61/2in 12in 25in 28.4° Within
63/4in 101/2in 24in 32.7° Within
63/4in 11in 241/2in 31.5° Within
63/4in 111/2in 25in 30.4° Within
7in 10in 24in 35.0° Within
7in 101/2in 241/2in 33.7° Within
7in 11in 25in 32.5° Within
71/4in 10in 241/2in 35.9° Within
71/4in 101/2in 25in 34.6° Within
71/2in 10in 25in 36.9° Within
Asked about this

Questions people search for

What is the 7-11 rule for stairs?
A 7 inch riser with an 11 inch tread. Two risers and one tread come to 25.00 inches, which is the top of the comfort band the pairs table on this page is drawn from.
What is the best rise and run for stairs?
By the same measure, a 6.50 inch riser against a 12.00 inch tread: two risers and one tread come to 25.00 inches.
Is a 9-inch step too high?
Yes, under both codes this site carries. The residential row on this page allows 7.75 inches and the accessible route row allows 7.00.

Building codes are adopted and amended locally. Confirm every figure with the code your jurisdiction has adopted before you cut.

Source

Where the limits come from

2 sources, with the date each was read

Building codes are adopted and amended locally. Confirm every figure with the code your jurisdiction has adopted before you cut.

Updated September 2026