Angle finder
An angle finder measures the angle between two surfaces or lines, in degrees. It can be a printed protractor, a sliding bevel, a digital angle finder with an LCD readout — or the phone in your pocket. Your iPhone already has the same tilt sensors as an electronic angle finder, so the right app turns it into one for free.
What is an angle finder?
An angle finder is any tool that tells you the angle where two faces meet. Hold it into a corner, against a roof rafter, or on a workpiece, and it reports how many degrees that angle is. The simplest version is the protractor you used in school; the most precise is a digital angle finder that reads the angle from an electronic sensor and shows it as a number.
The difference that matters is how you read the angle. A printed scale you eyeball is fine for rough work but easy to misread by a degree or two. A digital reading removes that guess — and that is exactly what a phone does, because every modern iPhone carries an accelerometer and gyroscope that sense the direction of gravity.
Protractor & bevel
The classic half-circle protractor and the sliding T-bevel. Cheap and reliable, but you read the angle by eye off a printed scale, so fine degrees are a guess.
Carpenter / miter angle finder
Two arms that hinge open against a corner — great for transferring a miter or a wall corner, but you still copy the angle onto a saw or a protractor to get a number.
Digital angle finder
An electronic gauge or digital bevel with an LCD readout in degrees. Accurate and fast, usually $20–$60, and one more tool to keep charged and calibrated.
Angle finder app
Your iPhone already has the same tilt sensors as a digital angle finder. An app reads them and shows the angle on screen — no extra hardware, and it is always in your pocket.
Your iPhone as a digital angle finder
A dedicated digital angle finder is essentially a tilt sensor with a screen. The Protractor app reads the tilt sensor your phone already has and shows the live angle of any surface you rest it on. Lay the phone on a sloped board and the number you see is that board's angle. Switch the reading to percent slope or an X-in-12 ratio and the same tool doubles as an inclinometer for roof pitch.
For an angle you can't lay the phone against — the splay of a chair leg, a corner above your reach — camera mode lets you line up on-screen arms with the edges and read the angle off the photo. It is the one angle finder you never leave at the workshop, and it is free to try. See exactly how it reads the sensors on how it works.
Digital angle finder vs. an app: which to buy?
A standalone digital angle finder ($20–$60) is worth it if you need a rigid straightedge you can clamp, set a saw against, or use in a dusty shop where you'd rather not bring a phone. An angle finder app wins on everything else: nothing to buy, multiple modes in one place, no separate battery to charge, and it is already with you when you notice a shelf looks crooked. Many tradespeople carry both — the gauge for set work, the phone for the ninety percent of measurements that are quick checks.
Measure any angle,
right from your pocket.
Protractor turns your iPhone into a precision angle finder, level and inclinometer. Measure anything, anywhere.
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