AngleDuo – Protractor

Two surfaces. One angle. On iPhone Duo, AngleDuo uses the hinge to measure the angle between two surfaces. Position the two halves against the surfaces and read the result. Hold the value with a tap or enable automatic capture, which waits for two seconds of stable readings. A held value stays available when you close the phone.

On other iPhones and iPads, measure two surfaces in sequence: capture the first, then move the same device edge to the second. The shared edge must be horizontal; this gravity-based method cannot measure a corner between vertical walls. On Duo, sequential measurement is available in Settings.

The level measures with the device resting on its back or standing on an edge. A moving shadow and a fixed scale show the tilt. Placement can be selected in Settings, where you can also find slope and roof-pitch values.

“Per cut” gives the saw setting for two equal miter cuts. An interior angle of 112° gives 34° per cut; 0° means a square cut. Find it on Duo’s supplementary inner pane or in Settings.

The spirit level is free. The angle finder includes 5 free measurements; after that, the one-time AngleDuo Pro purchase unlocks it without limit.

Measure angles without limit, with the hinge and on any iPhone. Also includes target angles with tolerance and relative zero.

Optional Pro purchases and restoration are handled by Apple through StoreKit. The app checks the purchase entitlement on your device. We do not receive your payment details. The number of free angle measurements used is counted on your device in the Keychain; it is not transmitted and is not reset by deleting local data. Deleting local measurements does not cancel a purchase.

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