Physical Screen Size & True PPI Calibrator
Web browsers only report software pixel coordinates. By aligning an ISO standard credit card against the screen, this tool calculates your exact physical diagonal display size in inches (e.g. 27", 24", 15.6", 14") and real hardware PPI.
Physical Screen Size & True PPI Calibrator
Web browsers cannot read physical inches without a real-world object. Calibrate with a credit card, coin, or ruler on any monitor, laptop, or mobile screen.
👆 Place your real credit card directly over the graphic above. Adjust the slider until the edges match your card exactly.
Calibrating... Adjust slider to your reference object.
Real-Time Screen & Viewport Inspector
Detected live from your browser's display environment and GPU rendering context.
How to Calibrate Screen Size on Mobile vs. Desktop
Everything you need to know about measuring physical screen inches and PPI density across phones, laptops, and monitors.
1Why is a credit card larger than my mobile screen?
Standard ISO 7810 credit cards are 85.60 mm (3.37 inches) wide. Almost all modern smartphones held in portrait orientation are only 58 mm to 74 mm wide (e.g. iPhone SE is 58.5 mm, iPhone 15 is 68.5 mm, S24 Ultra is 76 mm). That means a horizontal credit card is physically wider than your phone!
2How do I calibrate accurately on a mobile phone?
We provide three universal solutions for mobile phones:
- Card Short Edge (53.98 mm): Fits easily on every phone screen width.
- Standard Coin (23–25 mm): Pocket coins like a US Quarter, Euro 1€, UK £1, or India ₹5 fit comfortably on any screen.
- Rotate to Landscape: Phone width expands to 130–165 mm, easily fitting a full card.
3What is True Hardware PPI vs. CSS Viewport?
Browsers report CSS pixels divided by your device pixel ratio (DPR, usually 2x or 3x on Retina/OLED phones). Your hardware PPI is the real density of physical LEDs manufactured per inch. High PPI (>400 PPI on phones, >200 PPI on MacBooks) produces razor-sharp text with invisible subpixels.
4No physical card or coin handy?
Select the ⚡ Device Presets tab above to instantly apply factory hardware specifications for popular devices like iPhone 13/14/15/16 (6.1", 460 PPI), Galaxy S24 (6.2", 416 PPI), standard laptops (13.3", 14", 15.6"), and desktop monitors (24", 27", 32").