What a 7.5-inch riser paired with a 9.5-inch tread actually gives you — pitch, comfort, and code status — plus the calculator to size a full flight.
A 7.5-inch riser with a 9.5-inch tread is non-compliant under IRC 2021 (max riser 7.75″, min tread 10.0″), and non-compliant under the IBC commercial standard (max riser 7.0″, min tread 11.0″).
This pair is one step's geometry. To size a complete flight for your floor-to-floor height, enter your total rise in the calculator and it will hold the riser near 7.5″ while checking every code limit.
A 7.5-inch riser with a 9.5-inch tread produces a 38.3-degree pitch, which is near the steep end of what is normally built for a staircase. In practice that means it is space-saving but tiring on a long climb and demanding on the way down. Its Blondel value of 24.5 inches lands right in the 24–25 inch Blondel comfort band, so it should feel natural underfoot.
Across a typical flight of about 14 treads, the 9.5-inch tread depth works out to roughly 10.3 feet of horizontal run — a compact footprint. Note that this pairing does not meet the residential IRC because the 9.5-inch tread is under the IRC's 10-inch minimum, so it would need adjustment before use in a typical home.
Reach for this pairing when floor space is tight and a steeper, more compact stair is acceptable — for example a secondary, basement, or loft stair rather than the primary staircase. Whatever your floor-to-floor height, the calculator below will hold the riser near 7.5 inches, divide the rise into uniform steps, and check the result against the code you select.