Stair Calculator (Risers, Treads & Stringer)
Enter your total rise and target riser height and get the exact number of risers, the actual riser height once it is split evenly, the number of treads, and the total run for laying out your stringer. The math updates as you type.
Stair Calculator
Enter total rise, your target riser height, and tread depth. Risers always split the rise evenly — that is what keeps every step the same height.
Risers = total rise ÷ target riser height, rounded to the nearest whole riser (minimum 1). Actual riser height then re-splits the rise evenly across that many risers. Treads = risers − 1. Check your local code for maximum riser height and minimum tread depth before building.
How stair layout math works
You cannot just divide total rise by a “perfect” 7-inch riser and call it done — the result almost never comes out even. Instead, round to the nearest whole number of risers, then divide the total rise by that whole number to get the real, buildable riser height. Every riser in the run then comes out identical, which is both a code requirement and what keeps a stair from feeling uneven underfoot.
| Step | Example: 44 in rise, 7 in target riser, 10.5 in tread |
|---|---|
| Raw riser count | 44 ÷ 7 = 6.29 → round to 6 |
| Actual riser height | 44 ÷ 6 = 7.33 in |
| Treads | 6 risers − 1 = 5 treads |
| Total run | 5 × 10.5 = 52.5 in (4.38 ft) |
Note there is always one fewer tread than risers — the top landing or floor above serves as the final “tread.” Most residential codes cap riser height around 7–7.75 inches and require a minimum tread depth near 10 inches; always confirm the exact numbers for your jurisdiction before you cut a stringer.
Contractor Estimate Calculator (Excel & Google Sheets)
Turn a stair or deck build into a priced, itemized estimate — materials, labor, markup, and profit, auto-totaled. The estimate you hand the client after the layout is set.
Framing the stringer
Once you have the actual riser height and tread depth, lay those two numbers out on your framing square (or stringer layout tool) and step them off down the stringer board, riser-over-tread, riser-over-tread, for the full riser count. Cut the bottom of the stringer down by one riser height to account for the flooring/finish thickness at the base, and always cut a test stringer before you commit the full set.
Related calculators
Building the deck this stair lands on? Run your boards through the deck material calculator, and figure your stringer and tread lumber with the board foot calculator.
Frequently asked questions
How do you calculate the number of stair risers?
Divide the total rise by your target riser height and round to the nearest whole number — that is your riser count. Then divide the total rise by that whole number again to get the actual, buildable riser height, since it rarely divides evenly on the first try.
How many treads does a staircase have?
Always one fewer than the number of risers. The top step is the landing or floor itself, so a 6-riser stair has 5 treads.
What is a comfortable stair riser height?
Most residential codes allow a maximum of around 7 to 7.75 inches, with 7 inches being a common comfortable target. Check your local code, since maximums vary by jurisdiction.
Is this stair calculator free?
Yes — free, no sign-up. Enter total rise, target riser height, and tread depth, and read the riser count, actual riser height, tread count, and total run. Estimates only; confirm against your local code.
Materials + labor + markup with the margin math handled — works for any trade.