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Residential Stair Code: Riser, Tread, Headroom and Width (IRC)

By Builders-Tools · Updated · How we calculate

Most US towns build their residential code on the International Residential Code. These are its main stair rules.

The numbers

Rule IRC
Maximum riser height 7-3/4 in
Minimum tread depth 10 in
Variation in one flight 3/8 in
Minimum headroom 6 ft 8 in
Handrail height 34 to 38 in

Your town adopts a version of the code, sometimes with changes. Always check with your building department.

Laying out a stair

Measure the total rise and divide it into equal risers no taller than 7-3/4 in. The stair calculator does the math and flags anything outside these limits.

Sources

Sources last checked 1 November 2026.

Frequently asked questions

What is the maximum riser height for stairs?

7-3/4 in under the IRC.

What is the minimum tread depth?

10 in under the IRC.

How much headroom do stairs need?

6 ft 8 in under the IRC.

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