How many steps, and how tall is each one?
Risers, treads, total run, stringer length and angle from your floor-to-floor height. Free, no email required to see the math.
Your inputs
Finished floor to finished floor (or deck surface to grade).
We split the rise into equal risers no taller than this.
Nosing to nosing.
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Assumptions (tap to adjust)+
The math, in plain English.
Measure the total rise — finished floor to finished floor, or deck surface to the ground where the stairs land. We divide that by your target riser height and round up to get a whole number of risers, then divide the rise back out so every step is exactly the same height. That equal-riser rule is the whole game: a single step that's a half-inch off is what people trip on.
Treads are one fewer than risers because the top floor or deck is the last step. Total run is treads × tread depth, and the stringer length is the straight-line hypotenuse of rise and run — buy stock a foot longer to cover the cuts. Two stringers carry stairs up to 36" wide; go wider than that and add a third down the middle, especially on a deck where the treads take weather.
The code check compares your numbers to the IRC R311.7 limits that are commonly required in Washington: risers no taller than 7-3/4", treads at least 10" deep, and at least 36" wide. Those are the typical thresholds — your local building department has the final say, and the permit inspector will measure. Any stair on a deck more than a few feet off the ground also needs a graspable handrail and guards, which this tool doesn't size.
If the tread, framing, or ledger is the part that's failing rather than the layout, that's a repair job. CRM Services, LLC rebuilds deck stairs and landings across Clark County and can tell you whether the stringers are worth saving.
Stair questions
What's the ideal riser height?+
Around 7 to 7-1/2 inches feels natural to most people, paired with a 10 to 11 inch tread. The old carpenter check is rise + run ≈ 17-18 inches, or 2 × rise + run ≈ 24-25. Shorter risers with deeper treads are easier on knees, which matters on exterior stairs used every day.
What is the maximum riser height allowed in Washington?+
Washington adopts the IRC, and R311.7 sets residential risers at a maximum of 7-3/4 inches, treads at a minimum of 10 inches, and no more than 3/8 inch variation between the tallest and shortest riser in a flight. Those are the commonly required numbers — confirm with your jurisdiction, because amendments and commercial occupancies differ.
How many stringers do I need?+
Two for stairs up to 36 inches wide, three for anything wider — and many builders go to three at 36 inches anyway when the treads are 5/4 decking or composite, which sags more than 2× lumber. Stringers also need solid bearing at both ends; hanging them off a rim joist with a few screws is the most common failure we see.
Do deck stairs need a permit in Vancouver or Clark County?+
Typically yes for exterior stairs attached to a deck, especially when the deck is more than 30 inches above grade or the stairs are part of a new build or rebuild — confirm with the permit office (City of Vancouver or Clark County Community Development, depending on where you live). Replacing a few treads in kind is usually maintenance.
What's a comfortable stair angle?+
Between about 30 and 37 degrees. A 7-1/2 inch riser on a 10-1/2 inch tread lands right around 35 degrees. Steeper than 40 starts to feel like a ladder; shallower than 30 eats a lot of floor space and can make people short-step.
What if my rise gives me an odd riser height like 7.2 inches?+
That is normal — rounding the riser count up is what keeps every step under the code max. Mark 7.2" as 7-3/16" on the framing square and stay consistent. What you must not do is make the bottom or top riser different to "absorb" the remainder.
Related services
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