Stair Calculator
Enter the total vertical rise to calculate the number of steps, the rise per step, and the total run of your staircase.
Results
- Number of steps
- 14
- Riser height
- 7.71 in
- Total run
- 130 in (10.83 ft)
Estimates only. Round up and buy a little extra to account for waste, spills, and breakage.
Measure the total rise from lower floor to upper floor and this stair calculator works out the number of steps, the exact riser height, and the total horizontal run, so your stairs land within code and feel comfortable to climb.
Risers that vary by more than 3/8 inch within one flight are a tripping hazard and a code violation in most jurisdictions, which is why exact division matters.
Also works as a stair rise and run calculator, step calculator, and deck stairs calculator.
How to use the stair calculator
- Enter the total rise (floor to floor) in in.
- Enter the target riser height in in.
- Enter the tread depth in in.
- Optionally add a price to estimate the total project cost.
- Read your quantities instantly — no sign-up, and you can print the estimate to take to the supplier.
Worked example
Inputs
- Total rise (floor to floor)
- 108 in
- Target riser height
- 7.5 in
- Tread depth
- 10 in
Results
- Number of steps
- 14
- Riser height
- 7.71 in
- Total run
- 130 in (10.83 ft)
Using the example values above, the stair calculator returns 14 (number of steps). Change any field to match your own project and the numbers update instantly.
How do you calculate stairs?
Divide the total rise by your target riser height and round to a whole number of steps. Then divide the total rise by that number to get the exact riser. A 108 in floor-to-floor rise with a 7.5 in target gives 14 risers of about 7.71 in.
The number of treads is one less than the number of risers, because the upper floor serves as the final landing. Total run is treads × tread depth.
Code limits for rise and run
Most residential codes cap risers at 7.75 in and require at least 10 in of tread depth. Aim for 7 to 7.5 in risers; the classic comfort rule is rise × 2 + run ≈ 24 to 25 inches.
Always measure total rise from finished floor to finished floor, including the thickness of any flooring you have not installed yet.
Formula
Steps = round(total rise ÷ target riser). Riser = total rise ÷ steps. Run = (steps − 1) × tread depth.
Frequently asked questions
- What is a comfortable stair riser height?
- Most codes cap risers at 7.75 in; 7–7.5 in feels comfortable for most stairs.
- What tread depth should I use?
- Use at least 10 in of tread depth; deeper treads are easier to climb.
- How many steps for an 8-foot ceiling?
- About 13 to 14 risers once you include the floor structure; total rise is usually 105 to 110 inches for an 8 ft ceiling.
- What is the maximum riser height?
- 7.75 inches in most residential codes, with no more than 3/8 inch variation between risers in the same flight.
Related calculators
Stair Stringer Calculator
Calculate stringer length and notch dimensions for a staircase.
Deck Board Calculator
Estimate how many deck boards you need for your deck size.
Board Foot Calculator
Calculate board feet of lumber from thickness, width, length, and quantity.
Rafter Calculator
Calculate rafter length and count from span, pitch, and spacing.