Stair Calculator

Stair Calculator with Diagram

Measure the vertical distance between finished walking surfaces, including the future lower landing finish. The drawing below is a geometry example, not a cutting template. After calculating, your own flight appears with its rise, run and tread count.

Example shown: 56 in total rise, 8 risers, 7 treads at a 10 in going; upper landing is the last step.

How to Calculate Stair Risers and Run

Divide total rise by a whole number of risers to keep the finished steps equal. If you enter a maximum riser height, the tool rounds the required count up, then divides the total rise by that count. It does not round each step independently.

For a 56 in rise and 8 risers, each finished rise is 7 in. When the upper landing supplies the final step, there are 7 separate treads. At 10 in per tread the run is 70 in. Those dimensions are an arithmetic example, not a prescribed stair design.

A tread’s full board depth can include a nosing beyond the riser face. The input here is the repeated horizontal going, so adding an overhang to every run would overstate the flight’s footprint.

The Upper Landing Changes the Tread Count

The second option adds a top tread at the same height as the landing; it does not add another rise. Choose the arrangement that matches your connection detail. A landing halfway up a staircase is a separate platform: calculate each straight flight from its own finished levels and allocate landing space separately.

This deck stair calculator also works with metric dimensions. Changing units converts the dimensions already entered, while the riser count stays a count.

Stair Stringer Calculator: Layout vs Cut Length

The repeated rise and going set the stringer pitch. The tool reports the step pitch-line length: the diagonal distance across the repeated tread intervals. That is a geometry reference, not the stock board length to buy or a finished cut-line measurement.

For the 7-tread example, pitch is about 34.99° and the step pitch line is 85.45 in. End cuts, connection details and stock width still determine whether a real stringer can be laid out on a particular board.

Why tread thickness matters at the first step

For the modeled arrangement, where the bottom bears on the finished lower landing and equal-thickness treads sit on the seats, the first seat height is riser height − tread thickness. A 7 in rise with a 1.5 in tread has a 5.5 in first seat; the finished first step remains 7 in.

The top seat is below the upper walking surface by one rise plus tread thickness in the landing-as-last-step option, or by tread thickness when a separate top tread is flush. These vertical references do not specify a hanger, notch or top plumb cut.

Check the Flight Against Your Available Space

Enter the available horizontal run to compare it with the calculated footprint. If the flight exceeds it, the result shows the shortfall; it does not silently shorten the treads or change the riser count. Passing that comparison is not a headroom or code approval.

Before construction, resolve headroom, landing dimensions, clear width, guards, handrails, permitted riser and tread dimensions, stringer support and connection requirements for your project. This tool covers a straight flight only, with no winders or spiral geometry. For the deck’s separate surface-board order, use the decking calculator.