iOS & Android · Built for the jobsite
Feet, inches and fractions held as exact rationals, not decimals. Enter a run and a pitch, get the rafter. Enter a total rise, get the stair. Open any result and see the formula with your own numbers substituted into it.
In review for the App Store and Google Play. Works with no signal, on no account, with nothing to sign up for.
Every number on screen can be traced back to where it came from — the arithmetic, the formula, and the source of the constant.
Dimensions are held as exact rationals over integers, so
1/3 of 8' comes back as 2' 8" and sixteen risers add up to
the rise you entered — not to a sixteenth less. Only operations that genuinely
produce an irrational drop to floating point, and those flag themselves
≈. Set the display anywhere from 1/2 to 1/64.
Open any result to see the formula with your values substituted into it. Entered
values and computed values never look alike, so you can always tell what you typed
from what the calculator worked out. Cycling outputs name themselves —
PLAN RUN · 2 OF 3 — instead of making you count presses.
Each material constant shows its source and the date it was retrieved, and you can override any of them. Manufacturer figures and estimates are marked differently, because they are different things. An estimate you can't audit is a guess with a decimal point.
Framing, stairs, materials, cut angles and four trade packs — one app, no separate downloads.
Framing & roofing
Common rafters, regular hips and valleys, and jack schedules built from the full-precision common rather than a rounded step. Unequal-pitch hips, where the plan angle isn't 45° and the two cheek cuts don't add up to 90. Plumb, seat and cheek cuts, hip backing and drop, bird's mouth with HAP and throat, ridge deduction, overhang, rake walls and gable studs. Pitch as ratio, angle, percent or slope.
Stairs
Riser and tread solving, run-limited and riser-limited, with "it does not fit" treated as a real answer that names the binding constraint. Landings and multi-flight layouts, each flight solved and checked on its own. Stringer length, angle and throat. Stairwell opening with its measurement datum stated. Layout marks you can take to the board.
Materials
Concrete by volume or by bag, block and brick, stud takeoffs, sheet goods, board feet, rebar, roofing squares and bundles, siding, decking, tile and paint. Waste is its own visible line, never folded quietly into the total.
Cut angles
Crown at any spring angle and any wall angle, nested or flat, plus polygons, hoppers, tapered work and baluster spacing. Every saw setting names the board orientation it assumes — the same cut is a different number flat on the table than it is on edge against the fence.
The trades, included
Voltage drop and box fill. Pipe offsets, rolling offsets, volume and slope. Duct sizing, equivalent round and air heat. Bolt circles, tap drills, sine bar, speeds and feeds. All four sets are built in.
Built for the jobsite
Everything runs on the device — no account, no connection, nothing to wait for. Keeps the screen awake while you work. Keys sized for gloves. A high-contrast outdoor theme for bright sun. A running tape you can scroll back through, undo, and export.
Choose IRC 2021, IRC 2024 or your own local amendment. Every row shows the actual value, the required value, and the section it comes from — including the rows that pass.
If you think the calculator has a result wrong, tell us the inputs and what you expected. Every fix lands as a test before it lands as a fix.
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