420 × 912 viewport: which devices use it?
420 × 912CSS px · 19.5:9
420 × 912 is the CSS viewport of 1 device in our research, including the iPhone Air. Turned sideways it becomes 912 × 420.
| Device | CSS viewport | DPR | Physical pixels | Year |
|---|---|---|---|---|
| iPhone Air | 420×912 | 3 | 1260×2736 | 2025 |
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Designing for 420px wide
Breakpoints
Tailwind: base styles only (below sm, 640px). Bootstrap: xs. Sideways (912px): Tailwind md (sm: md: styles apply).
Room for content
388px with 16px side padding, 372px with 24px. Anything fixed wider than 420px makes the page scroll sideways (how to fix it).
Nearby sizes
Questions people ask
Which phone has a 420 × 912 viewport?
iPhone Air.
Is 420 × 912 the screen resolution?
No, it’s the viewport in CSS pixels. The physical screen has more pixels: the iPhone Air is 1260 × 2736 (DPR 3).
Which breakpoint does a 420px wide screen use?
Tailwind CSS: base styles only (below sm, 640px). Bootstrap: xs.
Guides that help
- What is a viewport? CSS pixels vs screen resolutionA viewport is the area your page is laid out in, measured in CSS pixels, not screen pixels. See real numbers from iPhones and MacBooks, then check yours.Guides · 8 min read
- How to fix horizontal scrolling on mobile (12 causes)Page wobbles sideways on phones? The 12 usual causes of horizontal scrolling on mobile, a fix for each, and a console snippet that finds the culprit fast.Fixes · 9 min read
- Responsive breakpoints in 2026 — the widths that matterWhere 123 real phones, tablets, laptops and monitors land in CSS pixels, which responsive breakpoints actually matter in 2026, and which screens to test.Guides · 8 min read