The reason

Do you ever wondered if your display is retina? At which distance your screen will look like a retina display? What is your display aspect ratio? Or maybe just want to know your screen PPI/DPI in order to configure Photoshop to see your images at an accurate print size, for that purpose I created this little calculator.

Aspect Ratio

Enter your screen aspect ratio, old TVs use 4:3 and modern TVs use 16:9, some computer screens use other aspect ratios like 16:10 for instance, you can choose a preset or specify your own value.

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Aspect Ratio From Dimensions

If you don’t know your screen aspect ratio enter your screen resolution in order to get your aspect ratio above.

x pixels.
Screen Dimensions

Enter your screen dimensions in inches in one of the following fields, this form will automatically change the values on the other fields based on the value you provide, if you only know the width, height or diagonal size it will calculate the other values for you.

Screen Resolution

Enter your TV or PC screen resolution in pixels, HDTV use 1920x1080px but some computers and TVs have different resolutions, some 4K screens have 3840x2160px, Apple MacBook Pro Retina have 2880x1080 and there is a lot more resolutions on mobile devices.

 

Result:
Extra info (Some retina devices)
Device Width Height Inches PPI Distance
MacBook Pro (Retina, 15-inch) 2880 1800 15.4 220 15.59
Google Nexus 10 2560 1600 10.055 300 11.45
MacBook Pro (Retina, 13-inch) 2560 1600 13.3 227 15.15
Toshiba KIRAbook 2560 1440 13.3 221 15.57
iPad Retina 2048 1536 9.7 264 13.03
Samsung I9500 Galaxy S4 1920 1080 5 440 7.8
Google Nexus 7 1920 1200 7.02 323 10.66
Google Nexus 4 1280 768 4.7 318 10.82
Samsung I9300 Galaxy S III 1280 720 4.8 306 11.24
iPhone 5 1136 640 4 326 10.55
iPhone 4 960 640 3.5 330 10.43
Samsung I9100 Galaxy S II 800 480 4.3 216 15.85