The standard rise and run for stairs is a maximum riser height of 7 3/4 inches and a minimum tread depth of 10 inches for residential buildings. Commercial stairs are slightly stricter: a maximum 7-inch riser height and a minimum 11-inch tread depth. These dimensions come from the International Residential Code (IRC) and the International Building Code (IBC), which most U.S. states and local jurisdictions adopt as their baseline.
Residential Stair Dimensions
For homes (including single-family houses, townhomes, and individual units in apartment buildings), the code allows a maximum riser height of 7 3/4 inches and requires a minimum tread depth of 10 inches. The minimum riser height is 4 inches, so very shallow steps aren’t allowed either. These numbers represent the legal limits, not necessarily what feels best underfoot. Many builders aim for a 7- to 7 1/2-inch rise and a 10- to 11-inch run as a comfortable sweet spot.
“Rise” refers to the vertical height of each step, measured from the top of one tread to the top of the next. “Run” (or tread depth) is the horizontal distance from the front edge of one step to the front edge of the step above, measured straight back. If you’re building or renovating stairs, these two measurements determine the angle of the staircase and how it feels to walk on.
Commercial Stair Dimensions
Stairs in commercial buildings, offices, schools, and public spaces follow stricter requirements: a maximum riser height of 7 inches and a minimum tread depth of 11 inches. The lower rise and deeper tread make stairs easier to navigate for large numbers of people, including those carrying items, wearing different footwear, or moving quickly during an emergency. If you’re designing anything that isn’t a private residence, these are the numbers to follow.
Why Consistency Matters More Than Size
Getting the right rise and run matters, but keeping every step identical within a single flight matters even more. Building codes require that the difference between the tallest and shortest riser in a flight not exceed 3/8 inch. The same 3/8-inch tolerance applies to tread depth variation.
Research on stairway falls shows why this rule exists. Variations as small as 6 millimeters (roughly 1/4 inch) between adjacent risers can disrupt your natural stepping rhythm and increase fall risk. One observational study found that 80% of fall-related events on stairs occurred on flights where the riser height varied by 14 millimeters (about 1/2 inch) and tread depth varied by 38 millimeters (about 1 1/2 inches) from step to step. A separate review of 80 stairway falls over 15 years found that 60% involved riser height inconsistencies greater than 3/8 inch.
Your body memorizes the step height after the first two or three steps and adjusts your gait automatically. When one step is even slightly taller or shorter than the others, your foot lands at the wrong time, and that’s when stumbles happen. If you’re building stairs yourself, measure carefully and double-check every riser and tread before finishing.
Nosing Requirements
The nosing is the front edge of the tread that overhangs the riser below. For residential stairs, nosing must project between 3/4 inch and 1 1/4 inches beyond the face of the riser. This overhang gives your foot a bit more surface to land on during descent without making the tread depth itself larger. If your tread depth is already 11 inches or more, nosing projection is not required.
Nosings must also be uniform throughout the flight, including the landing at the top. The leading edge needs a slight curvature or bevel (between 1/16 inch and 9/16 inch) to reduce the chance of catching your toe on a sharp edge.
Handrail Height and Grip Size
Handrails on stairs should be between 34 and 38 inches high, measured vertically from the stair nosing to the top of the gripping surface. For round handrails, the outside diameter should fall between 1 1/8 and 2 inches, which is the range most adults can comfortably wrap their fingers around. Non-circular handrails need a perimeter between 4 and 6 1/8 inches with a maximum cross-section of 2 1/4 inches. For children’s handrails, a maximum height of 28 inches is recommended.
How to Calculate Rise and Run for Your Staircase
Start by measuring the total vertical distance from the finished floor at the bottom to the finished floor at the top. This is your total rise. Divide that number by your target riser height (7 1/2 inches is a good starting point for residential stairs) to get the number of steps. Round to the nearest whole number, then divide the total rise by that number to get your actual riser height. Make sure it falls within the 4-inch minimum and 7 3/4-inch maximum for residential, or 7-inch maximum for commercial.
For example, if your total rise is 108 inches (9 feet), dividing by 7.5 gives you 14.4 steps. Round to 14, and your actual riser height is 108 divided by 14, which equals 7.71 inches. That’s under the 7 3/4-inch residential maximum, so it works. You’d then need at least 10 inches of tread depth per step, giving you a total horizontal run of about 130 inches (nearly 11 feet) for the staircase. If that footprint is too long for your space, adding one more step (15 risers at 7.2 inches each) shortens the total run and gives you a more comfortable step height.
Keep in mind that your local building department may have amendments that differ from the IRC or IBC. Some jurisdictions adopt stricter requirements, so check your local code before starting construction. Permit inspectors will measure both rise and run, and they will check for consistency across the full flight.