Published 1 September 2026 · Buying Guides · 2 min read
Projector Screen Calculator Guide: How to Use It
A field-by-field walkthrough of the free screen calculator, including the throw-distance and viewing-distance outputs people miss.
What the Calculator Does
Our screen calculator converts a diagonal size into width and height for a chosen aspect ratio, in inches, centimetres or feet, and adds two extra planning outputs: a suggested viewing distance range and, if you enter your projector's throw ratio, a projector throw distance.
Diagonal, Unit and Aspect Ratio
Enter your target diagonal and choose the unit it's in. Then pick an aspect ratio — 16:9 for widescreen video, 16:10, 4:3 for legacy/presentation content, 1:1 for square formats, or Custom to enter your own width:height ratio if your content or projector uses something else.
Reading the Viewing Distance Output
The viewing distance figure is a general guideline — roughly 1.5× to 2.5× the screen's width — shown in both feet and metres. Use it to sanity-check your seating distance against the size you're considering, in either direction: if your seating is closer than the low end, consider a smaller screen; if it's further than the high end, consider a larger one.
Using the Throw Ratio Field
Throw ratio is listed in your projector's own spec sheet as throw distance ÷ image width. Enter it in the optional throw ratio field and the calculator multiplies it by your calculated screen width to show how far from the screen the projector needs to sit — useful for confirming a ceiling mount position before installation.
Reset and Try Different Scenarios
Use the Reset button to return to the default 120-inch, 16:9 example and try different diagonals or ratios — nothing is sent anywhere, so it's safe to experiment with several sizes before deciding. Once you have a size in mind, browse matching products on our size guide.
