What Is a Comfortable Stair Riser Height?
The short answer
A comfortable stair riser is 7 to 7.5 inches (18-19 cm) tall, paired with a tread of 10 to 11 inches (25-28 cm). US residential code (IRC R311.7.5.1) allows risers up to 7¾ in - but that maximum is the legal ceiling, not the comfortable target:
- 7-7.5 in riser - the sweet spot. Easy climb, natural stride.
- 7¾ in riser - legal, but noticeably steep. Fine for a basement or attic run, tiring for a main stair.
- Over 7¾ in - fails the common US residential code limit.
- Under about 6 in - legal but awkwardly shallow; people shuffle or double-step.
The riser never works alone, though. What actually makes a stair feel right is the riser and tread together - and there’s a 350-year-old rule for that.
The comfort rule: 2 × riser + tread ≈ 24-25 in
A walking stride shortens as it climbs: every inch of height you step up costs about two inches of forward stride. The French architect François Blondel turned that into the step formula still used today:
2 × riser + tread = 24 to 25 inches
Inside that band, the stair matches a natural gait. Below it, steps feel choppy and cramped; above it, each step is a small lunge. This is the same check the Stair Calculator runs on every layout.
Riser height vs. comfort - the reference table
Here is the Blondel check (2 × riser + tread) for common riser heights, against the IRC limits of a max 7¾ in riser and min 10 in tread:
| Riser height | 2R + T, 10 in tread | 2R + T, 11 in tread | Verdict |
|---|---|---|---|
| 6 in (15.2 cm) | 22 in | 23 in | Too shallow - choppy stride, eats floor run |
| 6.5 in (16.5 cm) | 23 in | 24 in | Comfortable with an 11 in tread |
| 7 in (17.8 cm) | 24 in | 25 in | The sweet spot - works with either tread |
| 7.5 in (19.1 cm) | 25 in | 26 in | Comfortable with a 10 in tread |
| 7¾ in (19.7 cm) | 25.5 in | 26.5 in | Code max - legal, but past the comfort band |
| 8 in (20.3 cm) | 26 in | 27 in | Over the IRC riser limit - fails code |
Two things fall out of the table:
- Steeper riser wants a shallower tread, and vice versa. A 7.5 in riser with an 11 in tread totals 26 in - each is fine alone, together they overshoot.
- The code maximum is not the comfort target. At 7¾ in even a minimum 10 in tread lands at 25.5 in, just past the band. Aim for 7-7.5 in and treat 7¾ in as the escape hatch for tight spaces.
You can’t just pick a riser - the rise decides
Here’s the catch every first-time stair builder hits: every riser in a flight must be equal, so the real riser height is your total floor-to-floor rise divided by a whole number of steps. You choose the step count; the arithmetic chooses the riser.
Take a 108 in rise (2.74 m, a clean 9 ft) with 10 in treads:
- Aim for 7 in risers: 108 ÷ 7 = 15.4, round to 15 risers. Actual riser: 108 ÷ 15 = 7.20 in. Comfort: 2 × 7.20 + 10 = 24.4 in - squarely in the band.
- Aim for 7.5 in risers: 108 ÷ 7.5 = 14.4, round to 14 risers. Actual riser: 108 ÷ 14 = 7.71 in. Comfort: 2 × 7.71 + 10 = 25.4 in - a shade past the band, and near the 7¾ in code cap.
Both flights are legal. The 15-riser version climbs at 37.7° and needs 140 in of run (14 treads × 10 in); the 14-riser version is steeper at 39.7° and needs 130 in. So the comfortable stair costs one extra step and 10 in of floor space - that trade, comfort against room, is the actual decision behind “what riser height should I use?”
👉 The Stair Calculator runs this live - enter your total rise, try target risers of 7 and 7.5 in, and it solves the riser count, the exact even riser height, total run, stair angle and stringer length, then flags whether the layout is inside the code limits and the 24-25 in comfort band.
Watch-outs
- Measure the true floor-to-floor rise - finished floor to finished floor, not the ceiling height. Getting this wrong throws off every riser.
- Keep every riser equal. The IRC allows at most 3/8 in of variation across a flight; the one odd step is the one people trip on.
- Codes differ by building type and place. The 7¾ in / 10 in limits are US IRC residential numbers. Commercial stairs under the IBC are stricter - max 7 in riser, min 11 in tread - and local codes can amend either. Always confirm yours.
- Don’t chase the minimum step count. Fewer, taller risers save run but sit at the steep edge of legal. On a stair you’ll climb daily, the extra step is worth it.
Related
- Stair Calculator - risers, exact riser height, treads, run, angle and stringer length with live code and comfort checks.
- Stairs & Railings tools - the full stairs toolset.
- How many stairs for a 9-foot ceiling - turning your rise into a step count.
- How far can a 2x8 deck joist span - another build number, worked out the same way.