Stair Calculator
Enter your total rise and this calculator finds the ideal number of steps, exact riser height, run per step, and total horizontal run.
Example
For a total rise of 108 in with a 7 in target riser: 108 / 7 = 15.4, rounded to 15 risers. Each riser is 108 / 15 = 7.20 in, giving 14 treads (steps). With a 10 in run per step, the total run is 14 x 10 = 140 in (about 11 ft 8 in).
How it works
Divide total rise by a target riser (~7 in) and round to the nearest whole number of risers, then divide total rise by that count for the exact riser height. Steps (treads) equal risers minus one, and total run equals treads times the run per step.
Good to know
This Stair Calculator turns a single floor-to-floor measurement into a complete staircase layout: how many treads you'll walk on, how many risers the staircase needs, the exact height of each riser, the run (depth) of each tread, and the total horizontal distance the stairs will eat up. It's aimed at DIY builders, deck and porch makers, remodelers, and anyone roughing out a stairway before cutting stringers or committing floor space.
Reach for it early in planning, when you know your total rise but haven't decided on a step count. The most common use is checking whether a comfortable staircase will even fit a given footprint, since the "total run" figure tells you how far the bottom step will project from the wall or landing. Adjust the target riser up or down and watch how the step count and run change, so you can trade a steeper climb for a shorter footprint or vice versa.
To read the result, start with the riser height: it should land near 7 inches and stay under roughly 7.75 inches for comfort and code. Then check that risers always come out one greater than treads, because the top floor itself serves as the final landing. The total run is simply tread count times the run per step, so a longer, gentler stair needs more floor length.
- Keep every riser identical: building inspectors flag staircases where the tallest and shortest risers differ by more than about 3/8 inch, and uneven steps are a genuine trip hazard.
One caveat worth remembering: this tool measures total rise from finished floor to finished floor, so factor in flooring thickness and any landing or trim before you cut. The numbers here are a fast, reliable starting point, but always confirm riser, tread, and headroom limits against your local building code before building.
Frequently asked questions
Why is there one more riser than the number of steps?
The top floor acts as the final landing, so the staircase climbs one riser past the last tread you step on. That is why risers always equal treads plus one, and total run is based on the tread count.
What riser height and tread run are considered safe?
Many building codes cap riser height around 7.75 in and require a tread run of at least 10 in. A riser near 7 in paired with an 11 in run is widely considered the most comfortable ratio.
Is my data uploaded anywhere?
No — this calculator runs entirely in your browser. Your inputs never leave your device, and it works offline once loaded.
Is this calculator free?
Yes, completely free with no sign-up and no limits.
People also ask
How do I measure the total rise for a staircase?
Measure the vertical distance from the finished floor at the bottom to the finished floor at the top, including any flooring or landing material. This single number is the total rise the calculator divides into equal risers.
What is the ideal riser height for stairs?
Around 7 inches is considered the most comfortable, with most codes capping risers near 7.75 inches. Lower risers feel gentler but require more steps and a longer total run.
What's the difference between rise and run on stairs?
Rise is the vertical height of each step (the riser), while run is the horizontal depth of each step you walk on (the tread). Total rise is the full floor-to-floor height, and total run is the overall horizontal length of the staircase.
How much horizontal space do my stairs need?
Multiply the number of treads by the run per step to get the total run. For example, 14 treads at 10 inches each need 140 inches, or about 11 feet 8 inches of floor length.
How many steps do I need for an 8-foot ceiling?
An 8-foot floor-to-floor rise is roughly 105 to 109 inches once you include the floor structure. At a 7-inch target riser that works out to about 15 risers and 14 treads, but enter your exact measured rise for precise numbers.
Why don't my risers come out to exactly 7 inches?
The calculator rounds the total rise to a whole number of risers, then divides the rise by that count for an exact, equal riser height. That final figure rarely lands on a round 7 inches, which is normal and keeps every step identical.
Can I use this stair calculator in centimeters or metric units?
The tool is labeled in inches, but the math is unit-agnostic, so you can enter centimeters in every field and the riser height, run, and total run will all be returned in centimeters.
Does a steeper riser save floor space?
Yes. Raising the target riser produces fewer, taller steps, which shortens the total run and footprint, but it also makes the climb steeper and can push you past comfortable or code-allowed limits.
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