Screen Size Calculator & Viewport Simulator
Stop guessing your layout numbers. We take the raw specs—diagonal size, resolution, and DPR—and do the math to show you exactly what the browser sees.
Common Device Viewports (2025)
| Device | Physical Size | Resolution | Viewport (CSS) |
|---|---|---|---|
| iPhone 16 Pro Max | 6.9" | 1320 × 2868 | 440 × 956 |
| iPhone 15 Pro | 6.1" | 1179 × 2556 | 393 × 852 |
| Google Pixel 8 | 6.2" | 1080 × 2400 | 412 × 915 |
| MacBook Air 13" | 13.6" | 2560 × 1664 | 1280 × 832 |
Frequently Asked Questions
How do I calculate physical screen size to pixels?
To convert physical size to pixels, you need the PPI (Pixels Per Inch). Pixels = Inches × PPI. Our calculator handles this conversion automatically using the diagonal size and resolution.
What is the most common mobile viewport size in 2025?
Most modern smartphones like the iPhone 15 and 16 use a viewport width of 393px or 430px. High-end Android devices often range from 360px to 412px in CSS pixels.
What is the viewport size of the iPhone 15 Pro?
The iPhone 15 Pro has a viewport size of 393 × 852 CSS pixels with a 3x Device Pixel Ratio (DPR).
Why use CSS pixels instead of physical pixels for layout?
CSS pixels (device-independent pixels) ensure that your UI elements appear at a consistent physical size regardless of the screen's literal pixel density (Retina/High-DPI).