iPhone Duo Simulator

The iPhone Duo has a 5.4″ outer display (1398 × 2034 pixels, 460 ppi) and a 7.6″ inner folding display (2670 × 1878 pixels, 430 ppi). Apple measures them as 5.36″ and 7.58″ as standard rectangles.

Folded, Safari gives a web page 382 CSS px of width, because iOS 27 keeps an 84pt column for the camera, status and Safari buttons on the right of the 466 × 678 pt screen. Unfolded in landscape the page is 951 CSS px wide. Device pixel ratio is 3.

The crease is barely visible, but it runs down the exact center of the unfolded screen at x = 475.5 CSS px. Headlines, buttons and form fields centered on the page sit right on the fold, which is where the hinge flexes and where the screen is split when the phone is half-open. DuoBreak lists every heading, link and but

For web testing, people use the words interchangeably. Apple's iPhone Duo simulator in Xcode runs native apps on a Mac. A browser-based emulator like DuoBreak or Chrome DevTools only changes the viewport size and user agent. DuoBreak goes further by measuring overflow, the right-side Safari column and the center crease

Each check is $1, paid once through Stripe Checkout. There is no account or subscription. You get both screenshots, a Duo score out of 100 and the list of issues.