Stair Layout for 126" total rise (10.5 ft)
The exact step count, riser height, tread depth, and stringer length for a 126" total rise (10.5 ft) staircase. Adjust any field below to try your own numbers.
Number of Steps
18
Riser Height
7"
Tread Depth
10.5"
Total Run
189"
Stringer Length
227.15"
Stair Angle
33.7°
Code check: riser OK (≤ 7.75") · tread OK (≥ 10") · comfort sum (2×riser+tread) 24.5" (target ~24-25")
Result
A total rise of 126" split into 18 steps gives a 7" riser and a 10.5" tread — a stringer length of 227.15" at a 33.7° angle. Both dimensions fall within common code limits.
Riser height vs. resulting tread depth
What is a Stair Calculator?
Designing a safe, comfortable staircase means dividing a fixed vertical height (the total rise) into a whole number of equal steps, then choosing a tread depth that feels natural to walk on — every riser in a flight must be exactly the same height, since an uneven step is a well-known trip hazard. This calculator takes your total rise and a target riser height, works out the closest whole number of evenly-sized steps, and derives the tread depth, total horizontal run, stringer (diagonal support board) length, and stair angle from there.
It also checks your numbers against common residential building-code limits — a maximum riser height and a minimum tread depth — though exact requirements vary by location, so always confirm against your local code before building.
Riser Height Options for a 126" Total Rise
Holding the total rise fixed, here's how the step count, tread depth, and stringer length change across a range of common riser heights.
| Riser Height | Steps | Tread Depth | Stringer Length |
|---|---|---|---|
| 6" | 21 | 12.5" | 291.17" |
| 6.5" | 19 | 11.24" | 247.96" |
| 7" (current) | 18 | 10.5" | 227.15" |
| 7.25" | 17 | 10" | 211.6" |
| 7.5" | 17 | 10" | 211.6" |
| 7.75" | 16 | 10" | 203.66" |
Stair Formulas
Because the number of steps must be a whole number, the riser height almost never comes out to exactly your target — the calculator rounds to the nearest whole step count, then recalculates the exact riser height needed so every step is identical.
The Riser-Tread Comfort Formula
A widely used rule of thumb says a comfortable staircase should satisfy roughly "2 × riser height + tread depth = 24 to 25 inches." Taller risers pair with shallower treads and vice versa, because the formula approximates a natural stride length — a very steep stair (tall risers, shallow treads) feels cramped and tiring, while an overly shallow one (short risers, deep treads) forces an awkward, extra-long step between each level.
Common Residential Code Limits
Typical residential building codes cap riser height at around 7.75 inches and require a minimum tread depth of about 10 inches, with a minimum stair width around 36 inches and at least 6 feet 8 inches of headroom throughout the flight. Handrails are usually required between about 34 and 38 inches above the tread nosing, and guards are required once the total rise exceeds about 30 inches. These figures vary by jurisdiction, so always check your local code before finalizing a design.
Stringer Length and Stair Angle
The stringer is the diagonal structural board that the treads and risers attach to — its length is simply the hypotenuse of a right triangle formed by the total rise (vertical leg) and total run (horizontal leg), found with the Pythagorean theorem. The stair angle (measured from horizontal) comes from the inverse tangent of rise over run; most comfortable stairs land somewhere between about 30 and 35 degrees — steeper than that starts to feel more like a ladder than a staircase.
Example — Your Current Inputs
A total rise of 126" split into 18 steps gives a 7" riser and a 10.5" tread — a stringer length of 227.15" at a 33.7° angle. Both dimensions fall within common code limits.
Additional Example — A Standard 8-Foot Basement Stair
An 8-foot (96 inch) basement staircase targeting a 7-inch riser needs 96 ÷ 7 ≈ 13.7, rounded to 14 steps. The actual riser height becomes 96 ÷ 14 = 6.86 inches, comfortably under the 7.75-inch code limit, with a comfort-formula tread depth of about 10.8 inches — landing right in the typical residential range.
About These Parameters
- Total Rise
- The full vertical height the staircase must climb, floor to floor (or floor to landing for a stair with a mid-flight landing).
- Target Riser Height
- Your preferred riser height — the calculator finds the closest whole number of equal steps to this target, since the total rise rarely divides evenly.
- Number of Steps / Tread Depth Overrides
- Leave these blank to let the calculator derive them automatically, or set either one directly if you already know exactly how many steps you want or exactly how deep the treads need to be.
- Stair Width
- The usable clear width of the staircase — mainly informational here, though it matters for material and cost estimates and for meeting code minimums.
Frequently Asked Questions
Why doesn't my riser height come out to exactly what I entered?
Because the number of steps must be a whole number, but the total rise rarely divides evenly by your target riser height. The calculator rounds to the nearest whole step count first, then spreads the total rise evenly across that many steps — every riser in the flight has to be identical, so the result is usually a fraction of an inch off your original target.
How many treads are there compared to risers?
In many real staircases, the number of treads is one fewer than the number of risers, since the top step lands directly on the upper floor and doesn't need its own tread board. This calculator uses the step count for both figures for simplicity — treat total run as an estimate and confirm the exact tread count against your framing plan.
What stair angle is considered comfortable?
Most comfortable residential stairs land between about 30 and 35 degrees from horizontal. Steeper stairs (over roughly 40-45 degrees) start to feel more like a ladder, while very shallow stairs (under 25-30 degrees) take up a lot of horizontal space for the same total rise.
Does this calculator guarantee my stairs meet code?
No — it checks your numbers against commonly cited residential limits (riser height, tread depth), but exact building code requirements vary by state, city, and stair type (interior vs. exterior, spiral, etc.). Always verify against your local building code or with a professional before construction.