Quick answer: Both phones unfold to a 7.6-inch inner display, but they are not the same panel. The iPhone Duo inner is 2670 × 1878 at 430 PPI with a 10:7 aspect ratio. The Galaxy Z Fold8 inner is 2448 × 1848 at 403 PPI with a 4:3 ratio. On the cover, the Duo is 6.3 inches (19.5:9); the Fold8 is 6.4 inches (21:9).
If you are choosing between them for reading width, video, or responsive layout work, compare diagonals and resolutions together. A tied inch count can still mean a different usable canvas.
iPhone Duo vs Galaxy Z Fold8 at a glance
| iPhone Duo | Galaxy Z Fold8 | |
|---|---|---|
| Form factor | Book-style fold | Book-style fold |
| Cover diagonal | 6.3″ | 6.4″ |
| Cover resolution | 1206 × 2622 | 1080 × 2520 |
| Cover aspect | 19.5:9 | 21:9 |
| Inner diagonal | 7.6″ | 7.6″ |
| Inner resolution | 2670 × 1878 | 2448 × 1848 |
| Inner aspect | 10:7 | 4:3 |
| Inner PPI | 430 PPI | 403 PPI |
| Refresh rate | 120Hz ProMotion | 120Hz |
| Peak brightness (inner) | 3000 nits (outdoor) | 3000 nits |
Numbers come from our device catalog. Open the full spec sheets on the iPhone Duo and Galaxy Z Fold8 pages, or use the interactive side-by-side compare tool.
Cover display: closed phone use
When folded, both devices behave like tall smartphones with an outer screen.
The iPhone Duo cover is slightly narrower in diagonal (6.3″ vs 6.4″) but packs more vertical pixels (2622 vs 2520 on the long edge). Aspect ratio is 19.5:9, close to modern slab iPhones. If you already design for a 6.3″ iPhone layout, the closed Duo should feel familiar.
The Galaxy Z Fold8 cover is 21:9, a bit taller and narrower in proportion. Samsung has tuned Flip and Fold cover screens toward full-app use in recent generations, but the CSS width you see in Chrome or Samsung Internet still lands in phone territory, not tablet territory.
For buyers, the practical gap on the cover is small. For developers, do not assume one cover viewport fits both without measuring on hardware.
Inner display: same 7.6 inches, different shape
This is where the comparison usually surprises people.
Samsung and Apple both advertise 7.6 inches on the inner panel. Diagonal alone does not tell you how wide the canvas feels.
- iPhone Duo (10:7) is wider relative to its height. You get more horizontal room for split view, spreadsheets, and two-column web layouts.
- Galaxy Z Fold8 (4:3) is squarer in the classic tablet sense. It can feel taller in portrait and less ultrawide in landscape than the Duo inner.
The Duo also pushes more pixels (2670 × 1878 vs 2448 × 1848) and a higher listed PPI (430 vs 403). Sharper UI and more bitmap headroom on the Duo; the Fold8 still has a sharp Dynamic AMOLED 2X panel by any normal standard.
Line them up visually on foldable screen sizes (proportional open/closed outlines) or compare iPhone Duo vs Galaxy Z Fold8 at true relative scale.
Physical size when folded and unfolded
Folded footprint affects pocket feel; unfolded width affects two-handed grip.
| State | iPhone Duo | Galaxy Z Fold8 |
|---|---|---|
| Folded (W × H) | ~73.5 × 160.9 mm | ~68.1 × 158.4 mm |
| Folded thickness | ~8.9 mm | ~12.1 mm |
| Unfolded width | ~143.5 mm | ~123.9 mm |
The Fold8 is narrower when folded but thicker in the closed stack. The Duo spans wider when open (143.5 mm vs 123.9 mm), which matches the wider 10:7 inner aspect.
Inner active area in our database lists roughly 6.48 × 4.64 inches for the Duo and 6.35 × 4.88 inches for the Fold8 inner. Different width/height tradeoffs even when the diagonal matches.
Video, reading, and multitasking
16:9 video on the inner screen will letterbox differently on each phone. The Duo’s wider aspect can leave more side margin in portrait; the Fold8’s 4:3 inner can feel closer to an iPad-style canvas for documents.
Reading and web often favor the Duo’s extra inner width. Note-taking and apps built for 4:3 tablets may feel more at home on the Fold8 inner.
Neither inner is a laptop replacement. Both are large phones that bend. The question is which rectangle you prefer for the apps you live in.
CSS viewport and breakpoints
Foldables need two layout targets minimum: cover (phone-narrow) and inner (tablet-wide). The Duo and Fold8 will not report identical window.innerWidth values even when their inner diagonals match.
We do not publish verified CSS viewport sizes until they are measured on device. Plan layouts with ranges, then confirm on hardware:
- Viewport checker on each phone, folded and unfolded.
- Breakpoint checker for Tailwind-style cutoffs.
- Viewport vs screen width vs DPR for why marketing pixels are not CSS pixels.
For cover-only behavior, see iPhone Duo inner vs outer display and the Android-focused CSS viewport sizes on Android (same conceptual split, different OEM scaling).
Which foldable screen fits you?
- Tighter folded width, thicker closed phone: Galaxy Z Fold8.
- Thinner fold stack, wider open canvas, higher inner PPI: iPhone Duo.
- Ecosystem and apps: that decision is outside screen geometry, but both inner panels are large enough that poorly responsive sites will show it immediately.
Still undecided? Compare every display spec in one view, or browse all foldable screen sizes including Galaxy Z Fold8 Ultra (8.0″ inner) if you want a larger Samsung panel.
FAQ
- Is the iPhone Duo inner screen bigger than the Galaxy Z Fold8?
- Both list a 7.6-inch inner diagonal. The Duo has a wider 10:7 aspect ratio and higher resolution (2670 × 1878 vs 2448 × 1848). Bigger in inches is tied; bigger in usable width favors the Duo.
- Which cover screen is larger?
- The Galaxy Z Fold8 cover is 6.4 inches versus 6.3 inches on the iPhone Duo. Aspect ratios differ too: 21:9 on the Fold8, 19.5:9 on the Duo.
- Which has sharper inner display PPI?
- The iPhone Duo lists 430 PPI on the inner panel; the Galaxy Z Fold8 lists 403 PPI. Both are high-density OLED displays.
- How do I compare iPhone Duo and Galaxy Z Fold8 screen size online?
- Use our iPhone Duo vs Galaxy Z Fold8 comparison page for resolution, PPI, and dimensions, or the foldable hub to filter book-style foldables.
The short answer
iPhone Duo and Galaxy Z Fold8 share a 7.6-inch inner marketing number but not the same panel shape or pixel grid. The Duo is 10:7 at 2670 × 1878; the Fold8 is 4:3 at 2448 × 1848. Covers are 6.3″ vs 6.4″ with different aspect ratios.
Next: full compare view, iPhone Duo cover vs inner guide, or mobile screen sizes in 2026.
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