Total rise
measure from the finished floor at the bottom to the finished floor at the top, in inches.
Calculator
Stair Tread Calculator
Enter your total rise, total run, stair width and landings to estimate the number of risers and treads, riser height, tread depth, stair noses and the flooring needed for your stairs. All measurements are in inches.
Calculate your stairs
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The calculator divides the total rise by a 7-3/4 in maximum riser to find the number of risers, rounding up. Treads are one fewer than risers. Tread depth is the total run divided by the number of treads.
Results are checked against common residential code limits: riser height 7-3/4 in or less (IRC R311.7.5.1), tread depth at least 10 in (IRC R311.7.5.2), stair width at least 36 in, and a 3/4 to 1-1/4 in nosing when tread depth is under 11 in. Local codes vary; confirm with your building department.
How to use this calculator
Total run
measure the horizontal distance from the face of the bottom riser to the face of the top riser. Leave it blank if you only need riser counts; flooring is then estimated with a 10 in tread depth.
Width
measure the stair width wall to wall, or to the outside of the stringer on an open side.
Landings
enter the number of landings that need a landing nosing.
Risers
choose Yes if the vertical risers will also be covered with flooring.
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Worked example
A 108 in total rise (a typical 9-foot floor-to-floor height) divided by 7.75 in is 13.94, which rounds up to 14 risers. Each riser is 108 / 14 = about 7-23/32 in (7.71 in). With 14 risers there are 13 treads, because the top floor serves as the last step.
Common questions
How many stairs for a 9-foot ceiling?
A 9-foot ceiling often means about 108 in from finished floor to finished floor once the floor framing is included. At a 7-3/4 in maximum riser, 108 in needs 14 risers of about 7-23/32 in and 13 treads. Measure your actual floor-to-floor rise, since framing depth varies.
What is the maximum riser height?
The International Residential Code (IRC R311.7.5.1) sets a maximum riser height of 7-3/4 in. Commercial stairs under the IBC generally use risers between 4 and 7 in. Local codes vary; confirm with your building department.
What is the minimum tread depth?
The IRC (R311.7.5.2) sets a minimum tread depth of 10 in, measured nosing to nosing. When tread depth is under 11 in, a nosing of 3/4 to 1-1/4 in is required. Local codes vary; confirm with your building department.
How much flooring do I need for stairs?
Multiply each tread's width by its depth plus about 1-1/4 in for the nose, add each riser's width times its height if you are covering risers, divide by 144 for square feet and add about 15% for waste. The calculator on this page does that math.
Do I count the top floor as a tread?
No. The upper floor acts as the final step, so a straight stair has one fewer tread than risers. For example, 14 risers means 13 treads.
Ready for your stair parts?
Pricing and turnaround are confirmed on your written quote.