Stair Calculator β risers, treads & run
Calculate the number of steps, riser height, tread depth and total run from a total rise, with comfort checks.
π Runs entirely in your browser. Your input and output are never sent to a server or stored β fully private.
Enter the total rise (floor to floor). Optionally set a target riser, a total run or a target tread.
About this tool
This stair calculator turns a single measurement β the total height you need to climb β into a complete staircase plan: the number of steps, the exact riser height, the tread depth and the total horizontal run. It also checks your design against common comfort and code guidelines, so the steps feel even and safe to walk. All of the calculation happens in your browser.
Frequently asked questions
What measurements do I need to start?
The one number you must provide is the total rise, meaning the finished floor-to-floor height the stairs have to span. You can optionally add the horizontal space available; from the rise the tool chooses a step count that keeps each riser a comfortable height and then works out the tread depth and total run.
What makes a staircase comfortable and safe?
Comfortable stairs follow rules of thumb such as twice the riser plus the tread landing near 63 to 64 cm (about 25 inches), with risers around 17 to 19 cm and treads at least 24 cm deep. The calculator flags values outside these ranges, but building codes vary by country and region, so treat the results as guidance and confirm against your local code.
Is anything I enter sent to a server?
No. The staircase is worked out entirely in your browser, so the dimensions you enter are never uploaded to or stored on any server.
Is there a formula for a comfortable step?
The long-standing rule of thumb is 2 Γ riser + tread β 63 cm (about 25 inches), derived from the length of an average stride. A 18 cm riser with a 27 cm tread gives 63 and feels natural; push the riser to 22 cm and the same formula demands a 19 cm tread, which is too shallow for a whole foot. Use it to sanity-check a design quickly, then confirm against the code that applies where you are building.
Does this account for building codes?
No, and you should not treat it as if it did. Maximum riser and minimum tread are set by local code and differ substantially β Japan's Building Standards Act, the IRC in the United States and Eurocode-derived national rules all draw the lines in different places, and requirements are stricter for public buildings than for a private house. The tool gives you geometry that divides evenly and feels comfortable; whether that geometry is permitted where you are building is a question for the code and, for anything structural, a qualified professional.