Find the number of steps, actual riser height, tread depth, total run, and stringer length for any staircase.
Enter your total rise and step measurements, then click Calculate
This free stair calculator turns your staircase's total rise into a precise, buildable step layout — the number of steps, the actual riser height (rounded so every step is identical), the tread depth, total run, and the stringer (diagonal support) length — plus a basic check against common residential code guidelines for riser height and tread depth.
Enter the total rise (the full vertical height the staircase needs to cover) and your desired riser height. The calculator divides total rise by desired riser height and rounds to the nearest whole number of steps, since a staircase must have a whole number of identical risers. It then recalculates the actual riser height as total rise ÷ number of steps — this is the number you'll actually build to. Using your entered tread depth, it multiplies by the number of treads (one fewer than the number of risers) to find the total run, then applies the Pythagorean theorem to the total rise and total run to find the stringer length.
DIYers building deck stairs, porch steps, or a basement staircase; contractors laying out a stringer before cutting; and homeowners checking whether an existing or planned staircase meets common comfort and code guidelines. It's a planning and layout tool — always verify final measurements and code requirements with your local building department before construction.
The exact formulas this calculator uses
Every riser in a staircase must be the same height, so the raw division result is rounded to the nearest whole step, and the riser height is then recalculated to fit evenly.
The top step of a staircase is the upper floor itself, so a staircase with N risers only has N−1 physical treads.
The stringer forms the diagonal (hypotenuse) of a right triangle whose two legs are the total rise and total run, so the Pythagorean theorem gives its exact length.
From measuring total rise to reading your stringer length
Measure the total vertical height from the lower floor to the upper floor, in inches.
Enter your target riser height — 7 inches is a common comfortable default.
Enter your planned tread (step) depth — 10 inches is a common minimum.
See the number of steps, actual riser height, total run, and stringer length, plus a basic code compliance check.
A standard interior staircase and a shorter deck staircase
Widely referenced U.S. model-code figures — always confirm exact requirements with your local building department
| Measurement | Common Guideline |
|---|---|
| Maximum riser height | 7.75 in |
| Minimum tread depth | 10 in |
| Riser height variance (largest vs. smallest in one flight) | 3/8 in or less |
| Minimum stairway width | 36 in |
| Minimum headroom clearance | 6 ft 8 in |
| Comfortable riser height (design target) | ~7 in |
| Comfortable tread depth (design target) | ~10-11 in |
These figures reflect commonly used residential guidelines similar to the International Residential Code (IRC), but exact requirements vary by jurisdiction, occupancy type, and whether the stairs are interior, exterior, or part of an accessibility path. Always confirm final dimensions with your local building department before construction.
This calculator provides layout math and a basic guideline check only. It is not a substitute for a licensed contractor, structural engineer, or your local building department's official code requirements.
Where accurate stair layout math matters
Lay out a new deck or porch staircase before cutting stringer boards.
Plan a basement finishing project's staircase to a comfortable, code-typical layout.
Get the exact stringer length before buying and cutting lumber for the job.
Verify whether an existing staircase's riser height falls within common comfort or code ranges.
Quickly rough out a staircase layout for a client estimate before detailed design work.
Practice stair layout math and understand the rise/run/stringer relationship.
What this stair calculator does well, and where it can't replace professional design
Avoid the most common stair-layout errors
Summary: This stair calculator turns your total rise into a buildable step layout — number of steps, actual riser height, tread depth, total run, and stringer length — with a basic guideline check, free and instant. Pair it with the Square Footage Calculator for surrounding landing area.
Common questions about stair layout and stringer calculations
Official code and safety references — not a substitute for a licensed contractor
Other home & project tools