Measure between two surfaces and keep the result when closed
Does AngleDuo – Protractor work on iPhone Duo?
Yes, the developer says so: AngleDuo reads the angle between two surfaces with the Duo's hinge, and a held reading stays available after you close the phone.
- App Store confirmedJulian Zefferer, the developer, in the App Store description for version 1.1 (released October 15, 2026), which says the hinge measures the angle between two surfaces and that a held value stays available when the phone is closed.
Adapted for the fold
- Book · Partly folded
The hinge measures
Put the two halves against two surfaces and read the angle between them; tap to hold it, or let it hold itself after two seconds of steady readings.
- Open · Inner display
A pane for miter cuts
Open, an extra pane gives the saw setting for two equal miter cuts.
About AngleDuo – Protractor
AngleDuo is an angle finder. On the Duo, you put the two halves against two surfaces and read the angle between them. A tap holds the value, or automatic capture holds it after two seconds of steady readings, and a held value stays available when you close the phone. An extra pane on the inner display gives a per-cut value: the saw setting for two equal miter cuts.
Evidence reviews
What we checked, when, and what the evidence establishes. Each record preserves the support label at that check.
· App Store page reviewed
App Store confirmed · iphone-duo
The App Store description mentions iPhone Duo: "On iPhone Duo, AngleDuo uses the hinge to measure the angle between two surfaces." (version 1.1, released October 15, 2026).
App version: 1.1.
Store text only: we haven't seen the app running, and the store page doesn't show how each pose is used.
View reviewed evidence ↗
Related guides
iPhone Duo poses: closed, open, book, standing and Split View
A plain-language guide to the ways you will hold iPhone Duo, what the phone itself does in each, and the apps and ideas that make the most of them. For anyone buying one, and for anyone building for it.
The best iPhone Duo apps so far (October 2026)
The apps worth installing now that iPhone Duo is on sale, from the apps Apple named as launch partners to indie apps whose developers have shown a real iPhone Duo layout, picked for what they do when you open the phone.
Do your apps work on iPhone Duo? What happens before they're updated
Every iPhone app opens on iPhone Duo, but only updated ones fill the inner display. What an app looks like before its developer adapts it, how to tell which are ready, and which popular apps have said so.
Is this your app?
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Sources: AngleDuo – Protractor on the App Store (apps.apple.com)
More for iPhone Duo
KeepCount
Tyler Hillsman / 1881 Digital, LLC
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Simulator verified: Tyler Hillsman, the developer, in a submission to FoldHunt on October 17, 2026, with an unframed screenshot of the app in the iPhone Duo simulator in the press kit (keepcount.app). The App Store seller is 1881 Digital, LLC. The release notes for version 1.8 (released October 12, 2026) say KeepCount now adapts to the iPhone Duo's inner and outer displays, with a tabletop layout when it's partly folded.
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- Closed
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- Open