ManextApps
Stair Calculator icon

Calculator · Android

Stair Calculator & Stringer

Type the total rise, the max riser height and the tread depth the way you measured them, and a side view of the stair redraws as you go. The straight stair is free, works offline and needs no account.

Get it on Google Play
Android 8.0 or newerWorks offlineNo accountPro $4.99 once
A straight stair drawn to scale with 14 risers, 13 treads and a 37.6° angleStringer layout on a 2×12 with numbered framing square marksAn L stair and a U stair with landing size and landing heightBaluster spacing: 12 balusters with an even gap of about 3 7/8 inchesThe shared PDF of a basement stair with its drawing, results and notesThe feet, inch and fraction keypad with a total rise of 9′ 2 1/2″The straight stair in the bright Outdoor light themeSaved projects: a basement stair, a back porch L stair and a deck rail section
Real screenshots from the app. Scroll sideways to see them all.

A worked example

Say the rise is 9′ 0″, the max riser 7 3/4″ and the treads 10″. You get 14 risers at 7 11/16″, with the exact 7.714″ under it. That's 13 treads, a total run of 10′ 10″, a stringer of about 14′ 1″ and a 37.6° angle. The bottom riser gets cut shorter by the tread thickness, and you'll see that cut too.

The free straight stair

  • A side view with total rise, total run, stringer and angle, drawn to scale from your numbers.
  • Riser count and height, tread count, total run, stringer length and the bottom riser cut.
  • Set a max riser and let the app pick the riser count, or set the count yourself.
  • Tread thickness, floor finish and nosing sit in a Details sheet with defaults, so you don't have to touch them.
  • A plain note compares your riser and tread with the limits you set.
  • A feet, inch and fraction keypad, or mm, cm and m. Answers round to 1/8″, 1/16″ or 1/32″.

Pro, $4.99 once

  • Stringer layout: numbered framing square marks along the board, with rise on the tongue and run on the blade. It counts stringers for your stair width, picks a stock length and checks the wood left under each notch on a 2×10 or a 2×12.
  • L and U stairs: a plan view and a side view with the landing. The risers split between the two flights, or you set the split yourself, and you get the landing size, its height and a headroom note.
  • Balusters: the count and the exact even gap for a rail section, starting from a 4″ max gap.
  • Projects and PDF: save a stair, rename it, copy it and open it later. Share a PDF with the drawings, results, stringer layout and a cut list for your crew.

Pro also removes the ads. Every Pro screen shows a sample first, so you'll know what you're getting before you pay.

Need rafters, concrete or drywall too? That's what Construction Calculator is for. This one's just for stairs, and it goes a lot further with them.

Questions

Is there a subscription?

No. The straight stair is free, and Pro is $4.99 once through Google Play. It restores on a new phone with the same Google account.

Are there ads?

The free version shows one small banner at the bottom of the Stairs, Projects and Settings screens. It won't cover your numbers, and Pro removes it.

Does it follow building code?

The notes compare your stair with the limits you set and with common US values. They're not a code approval. Check your local building code and talk to a qualified builder before you cut.

Does it work in metric?

Yes. Pick mm, cm or m in Settings instead of feet and inches.

More apps

All apps