Lengths
common stair tread lengths are 36, 42 and 48 in, with 60 or 72 in lengths used for wide stairs.
Stair dimensions
Stair Tread Dimensions: Depth, Rise, Width and Nosing
Stair dimensions are set by building codes. Most homes follow the International Residential Code (IRC), and most commercial buildings follow the International Building Code (IBC). All dimensions below are in inches. Local codes vary; confirm with your building department.
Residential vs commercial stair dimensions
| Dimension | Residential (IRC) | Commercial (IBC) |
|---|---|---|
| Riser height | 7-3/4 in maximum | 4 in minimum to 7 in maximum |
| Tread depth | 10 in minimum | 11 in minimum |
| Nosing | 3/4 to 1-1/4 in when tread depth is under 11 in | Check your local code |
| Stair width | 36 in minimum | Check your local code |
| Headroom | 6 ft 8 in minimum | Check your local code |
Common tread lengths and thicknesses
Thicknesses
common solid tread thicknesses are 1 in and 1-1/2 in.
Stair comfort rules
The 7-11 rule
a 7 in riser with an 11 in tread is a commonly cited comfortable stair.
2 risers + 1 tread
two riser heights plus one tread depth should total about 24 to 25 in. For example, 2 x 7 in + 11 in = 25 in.
How flooring thickness changes the first and last riser
When new flooring is added at the bottom of a stair, the floor rises and the first riser gets shorter by the flooring thickness. When flooring is added at the top landing or upper floor, the last riser gets taller. Adding new treads or caps to every step shifts each step equally, so the top and bottom risers are the ones that change. Riser heights within a flight should stay consistent, so plan for flooring thickness at both ends before parts are made.
Common questions
What is the standard stair tread depth?
The IRC sets a 10 in minimum tread depth for homes; the IBC sets 11 in for commercial stairs. Many stairs use 10 to 11 in. Local codes vary; confirm with your building department.
What is the maximum stair riser height?
The IRC allows a maximum riser height of 7-3/4 in. Commercial stairs under the IBC use risers from 4 to 7 in.
How wide should stairs be?
The IRC sets a minimum residential stair width of 36 in. Common tread lengths are 36, 42 and 48 in, with 60 or 72 in for wide stairs.
When is a stair nosing required?
Under the IRC, a nosing of 3/4 to 1-1/4 in is required when tread depth is under 11 in.
What is the 7-11 rule for stairs?
The 7-11 rule describes a comfortable stair with a 7 in riser and an 11 in tread. A related rule says two risers plus one tread should total about 24 to 25 in.
Ready for your stair parts?
Pricing and turnaround are confirmed on your written quote.