What Is Riser Height? | Stair Code Limits Explained

Riser height is the vertical distance between two stair treads, capped at 7 3/4 inches for U.S. residential stairs.

For the full breakdown, see our best 6 Inch Tall Riser guide.

If you’re planning a staircase or checking whether an existing one meets code, riser height is the measurement that matters most for safety and leg. It’s the vertical rise from the top of one tread to the top of the next, not the sloped distance along the stringer and not the horizontal tread depth. Keeping every riser within a fraction of an inch of its neighbors is what makes a stair predictable to climb.

How Riser Height Is Measured

Riser height is measured vertically between the nosings of adjacent treads, or between a landing and the adjacent tread. The tread is the flat surface you step on; the riser is the vertical face between treads. Measuring from the wrong points is the most common mistake — code language measures between nosing lines, never along the incline of the stair.

For a new staircase, the calculation starts with the total rise: the vertical distance from finished floor to finished floor. Divide that by a target riser count, round to a whole number, then divide the total rise by that final count to get each riser’s finished height. Always measure from finished flooring, not subfloor, since the added thickness changes the math.

Residential vs. Commercial Limits

The two model codes that govern most U.S. stairs set different maximums. The International Residential Code (IRC), which applies to one- and two-family homes, allows a maximum riser height of 7 3/4 inches. The International Building Code (IBC), which governs commercial buildings and egress stairs, caps risers at 7 inches. Some local codes also set a minimum of 4 inches.

Both codes enforce the same uniformity rule: the tallest riser in a flight cannot exceed the shortest by more than 3/8 inch. This consistency is the safety core of stair design — uneven risers disrupt walking rhythm and cause trips.

Open Risers and Local Amendments

Open risers — stairs with no vertical face between treads — carry an extra restriction in residential settings. If a 4-inch sphere can pass through the opening, the stair does not meet the IRC’s open-riser rule, a provision aimed at preventing children’s heads from getting trapped.

Local jurisdictions can and do amend the model codes. New York’s stair code, for instance, cites a maximum of 8 1/4 inches while keeping the same 3/8 inch variation limit. Los Angeles County has its own provisions as well. Before building, confirm which code edition your jurisdiction has adopted — the national numbers are a starting point, not the final word. The IBC’s riser language, which specifies vertical measurement between adjacent nosing lines, is the standard reference for how this dimension is defined.

Why Uniformity Matters More Than the Maximum

A stair with all risers at 7 1/2 inches feels safe. A stair with risers alternating between 6 1/2 and 8 inches feels dangerous, even if the average lands within code. The 3/8 inch uniformity rule exists because the human body adapts to a rhythm when climbing; a sudden change forces an awkward, off-balance step. Contractors and inspectors treat this tolerance as the binding constraint, since it’s easier to design for a consistent rise than to fix one after framing.

When measuring an existing stair, check every riser in the flight, not just one. Differences of a quarter inch are hard to see but easy to feel, and they’re the first thing an inspector measures.