iPhone Duo Simulator
Paste a URL and see your site at both displays — folded and unfolded, portrait and landscape — without the device and without Xcode.
Two honest limits. Viewport sizes are derived, not published: both Duo displays run at 3×, so the CSS viewport is device pixels ÷ 3 — outer 1398×2034 → 466×678, inner 1878×2670 → 626×890 (from our specs page). Apple has not published web viewport numbers; treat these as our reading, not a spec. Framing is blocked by most sites: a server that sends X-Frame-Options: DENY or a frame-ancestors CSP will show blank here — which is why this tool is built for your own site, staging, or localhost, and not for checking apple.com.
Viewport sizes
| Display | Pose | CSS viewport | Device pixels |
|---|
Both displays are 3× (430ppi inner, 460ppi outer), so CSS pixels = 1878×2670 and 1398×2034 divided by 3. Apple's own simulator in Xcode 27.1 drives the real thing — see what the Duo Simulator runtime does and does not do yet.
What to check at each size
- Fold continuity: scroll halfway down on the 626px viewport, then reload at 466px. Content above the fold should not jump, and nothing should sit under the hinge seam when unfolded.
- Reflow, not rescale: the inner display is wider, not taller — check that your grid actually gains a column instead of stretching.
- Safe areas: the Duo's content insets are asymmetric (the hinge side holds no camera cutout, the cover side does). Test with insets you can't fake in a plain frame.
- Sticky bars: bars move to the side on the inner display (vertical bars) — a top bar that was fine at 466px can overlap the fold at 626px.
- Touch targets: 44pt minimum holds on both displays; the cover display is the one people use one-handed.
- Text at 466px: the cover display is the narrowest viewport Apple ships — the 1.42 ratio problem starts here.
For the layout rules behind these, see Strike a Pose: Adaptive Layouts and Prepare Your App for iPhone Duo.
Unofficial tool. Not affiliated with, endorsed by, or sponsored by Apple Inc. Your URL is loaded by your own browser — nothing is sent to this site.