Measure Total Rise
Measure from the surface of the lower finished floor to the surface of the upper finished floor. This is the single most critical measurement — get it exact.
100% Client-Side · Your Measurements Never Leave
A stair stringer calculator determines IRC-compliant riser height, tread depth, stringer length, and cut angles from your total rise measurement. It verifies dimensions against building code maximums and outputs fractional-inch measurements ready for marking on a framing square.
Stair Dimensions
Measure from finished floor to finished floor above
IRC min: 10" (excl. nosing)
Typical: ¾" – 1¼"
Stringer Results
Risers
—
Riser Height
—
Treads
—
Tread Depth
—
Stringer Length
—
Cut Angle
—
Stair Angle
—
Total Run
—
Stringer Profile
Enter your total rise and hit Calculate to see the stringer profile.
How It Works
Auto-Calculate Risers
StairMaster divides total rise by an ideal 7" target to find the optimal number of risers, then calculates exact riser height to 1/16" precision.
IRC Code Check
Every dimension is checked against IRC R311.7: max 7¾" riser, min 10" tread, max ¾" variance between risers. Red/green badges show compliance instantly.
Cut Your Stringers
The SVG diagram shows exact notch dimensions. Set your framing square to the riser and tread measurements, mark your 2×12, and cut.
Why Precise Stringer Layout Matters
Building code exists because uneven stairs cause falls. The International Residential Code (IRC R311.7) limits maximum riser height to 7¾ inches and requires minimum tread depth of 10 inches. More importantly, the maximum variance between the tallest and shortest riser in any flight is just ⅜ inch. Eyeballing it won't pass inspection. StairMaster calculates every dimension to 1/16" precision so every step feels identical underfoot. Enter your floor-to-floor height, and the calculator determines the optimal number of risers, exact riser height, stringer length, and the cut angle for your speed square — all verified against IRC code before you pick up a saw.
Frequently Asked Questions
What is the building code for stair riser height?
The International Residential Code (IRC R311.7) limits maximum riser height to 7¾ inches (196mm) and requires minimum tread depth of 10 inches (254mm). The maximum variation between any two risers in the same staircase is 3/8 inch. Local codes may be stricter — always verify with your building department.
How do you calculate the number of stair risers?
Divide the total rise (floor-to-floor height) by your target riser height (typically 7" to 7.5"). Round to the nearest whole number — that is your riser count. Then divide the total rise by that count to get your exact riser height. Every riser must be identical within 3/8".
What angle should stair stringers be cut at?
Stair stringer angle depends on your specific rise/run ratio. Comfortable stairs typically fall between 30° and 37°. The cutting angle is calculated as arctan(riser height / tread depth). For a 7" riser and 10" tread, that is arctan(7/10) = 35°, which is considered ideal for residential stairs.