Birdsmouth: Framing Calculator

Birdsmouth is a construction calculator for framing carpenters. It does feet, inches and fractions the way you read them off a tape, and it keeps what you entered on the screen, so you can check your own work before you cut.

THE CALCULATOR IS FREE, AND STAYS FREE

• Add, subtract, multiply and divide in feet, inches and fractions
• Multiply or divide a measurement by a plain number — two thirds of a wall, or one stud bay repeated
• Convert between feet-inches, decimal feet and decimal inches
• Exact arithmetic. Fractions, not decimal dust
• Set your fraction resolution anywhere from 1/2 to 1/64
• When a shown value has been rounded to that resolution, the app says so, and the exact value is one tap away
• A real backspace key, so one mistyped digit does not cost you four re-entered measurements
• Works with no signal, anywhere on the site

THE LEDGER

Every calculation stays on the screen as its own entry, with its own label and its own result. Scroll back through what you have done. Change an entry you got wrong and it recomputes. Select a run of entries to see their total. This is the part that lets you audit the numbers before you cut them.

THE SOLVERS

• Stairs — riser count, riser height, tread depth, total run and stringer length, checked against the code limits you select, and told plainly when a result exceeds them
• Rafters — the common rafter with its birdsmouth and tail, and the hip, valley and jack rafters including the cheek cut
• Pitch and angle — move between pitch, slope and degrees, in either direction
• Right triangle and diagonal — square a wall, find a brace
• On-center layout — stud count and spacing across a run
• Concrete — cubic yards for slabs and footings
• Area and volume

Every solver carries a worked example with real numbers, and its result lands in the Ledger as an entry you can check and edit like any other. Long-press any key to find out what it does.

THE JOB LAYER

Save a Ledger under a job name and open it again next week. Your jobs live on your phone: no account, no sign-in, no sync, and nothing that can be taken away from you.

HOW IT IS SOLD

The calculator and the Ledger are free, permanently. Not a trial, not a session cap, and no wall when you open the app. One payment opens the Solvers and the Job Layer. Bought once, yours for good, on every iPhone signed in to the same