Hinge Angle Meter is a $0.99 app that reads the hinge of the iPhone Duo as a live angle gauge. One display shows a large angle while the other keeps the tools in reach, so the fold works like a digital bevel gauge.
The developer, Appsolute LLC, published the app on the App Store ahead of the iPhone Duo’s October 23 on-sale date. Maker Lev Kalashnikov says one feature came from a system quirk. The left display plays an animation while the hinge moves, and he could not find a way to turn it off, so he added a button that swaps the main interface between the two screens. The workaround became a control.
The Hinge Works as a Digital Bevel Gauge
On supported folding devices, the physical hinge becomes the measuring tool. The live angle appears large on one side, and you can swap the panels or rotate the interface by hand. Guidance comes through visuals, sound and haptics.
Apple’s iOS 27.1 SDK includes a hinge API that lets apps respond to the angle of the display as the iPhone Duo opens and closes. Hinge Angle Meter shows that angle live while the phone opens or closes.
Apple says the hinge is built from more than 100 components that control opening and closing and support the center of the display, and an integrated magnet array gives a secure closure.
Hinge Angle Meter bundles these tools on iPhone and iPad.
- Live angle measurement with exact 90° guidance
- Copy and reproduce an angle, with a complementary angle calculation
- Custom target angles
- Pitch and roll level with zero calibration
- AR distance measurement that places two points in the camera view
- Local measurement history
The Same Tools Run on iPhone, iPad and Apple Watch
On other supported iPhone and iPad models, the app uses the motion sensors for its angle and level tools. The Apple Watch app works on its own and turns the Digital Crown into a target-angle control, with Zero, Hold and saved readings.
The app needs no account, shows no ads, collects no analytics and works without an internet connection. Measurements stay on the device, and camera frames used for AR measurement are not stored or transmitted.
Appsolute LLC is also the studio behind Animated Knots Knots Knots and Kendama Tricks Library. Hinge Angle Meter costs $0.99, needs iOS 17 or later and watchOS 10 for the Apple Watch app, supports eight languages and weighs 12.7 MB. Up to six family members can use it through Family Sharing.
Download Hinge Angle Meter from the App Store
