Stair Stringer Calculator App with Code Checks and a Cut Sheet

The problem: stair math is easy to get wrong

A stair has to climb an exact total rise while keeping every riser equal, every tread comfortable, and the whole flight within code. Doing that by hand means dividing the rise, testing riser counts, checking riser height and tread depth limits, then transferring cut marks to a stringer board. A single rounding mistake repeats across every step and can fail inspection or feel wrong underfoot.

The solution: calculate, check, and cut from one screen

Stringer does the division and the code check for you. Enter the total rise and tread run, pick a building code, and the app lists every valid riser count with its riser height, tread depth, run, and pitch, then marks a recommended option in the comfort zone. From there you can open the stringer layout, read the plumb and level cut angles and throat depth, and export a cut sheet for the shop.

Why builders use Stringer

• Balanced riser and tread options: compare every valid riser count at a glance and pick the most comfortable, compliant stair instead of guessing.
• Code checks built in: see riser height, tread depth, pitch, and stair width measured against IRC, NCC, or Doc K, with a clear pass or verify flag.
• Stringer layout marks: get the framing square rise and run, plumb and level cut angles, first cut, throat depth, and board length needed to cut the stringer.
• Printable cut sheet: export an elevation drawing, code compliance table, and stringer layout as a PDF to share or print.

Built for real stair construction decisions

Stringer is useful when the rise is fixed and you need a stair that fits, feels right, and passes code. It handles standard or flush top construction, nosing, tread thickness, a dropped stringer for equal finished rises, stringer stock size, and stair width. You can also enter a stock price to estimate the stringer material cost before buying.

Unlike a paper calculation, a saved Stringer project can be reopened when the rise or run changes. Unlike a generic calculator, the layout is drawn, so you can see the elevation and the stringer before cutting an expensive board.

Use Stringer with other WoodCutTool tools

For a quick browser estimate without installing the app, use the free stair stringer calculator or the on-page Stringer calculator. To learn the fundamentals, read stair stringer design: rise and run basics and comfortable stair layout rules. For field measuring, see deck stair stringer field measurements.

Offline and simple by design

Stringer is designed for local calculation on iPhone. No account is required for the core workflow, so stair layout stays available on the job site, the deck, or the shop where internet access may be unreliable.

FAQ

What is a stair stringer calculator?

A stair stringer calculator takes the total rise and tread run of a stair and works out the number of risers, the riser height, the tread depth, the pitch, and the cut marks needed to lay out a stringer board.

How does Stringer calculate riser height?

Stringer divides the total rise across a range of riser counts to find balanced options, then checks each riser height and tread depth against the selected building code so you can pick a comfortable, compliant stair.

Which building codes does Stringer support?

Stringer includes IRC (US/CA), NCC (AU), and Doc K (UK) presets and shows riser height, tread depth, pitch, and stair width checks against the code you choose. Compliance results are estimates to verify on site.

Can Stringer produce a cut sheet?

Yes. Stringer shows an elevation view and a stringer layout with plumb and level cut angles, throat depth, first cut, and board length, and it can export a printable stair cut sheet through the iOS share or print action.

Does Stringer work offline?

Yes. Stringer is designed for offline iPhone use with no account required for the core workflow, so you can lay out a stair without a connection.

Is Stringer free?

Yes. Stringer is a free iPhone app, and WoodCutTool also offers a free browser stair stringer calculator for quick estimates.