Projector Screen Size Calculator

Enter your screen diagonal, width, or height along with an aspect ratio — and the Projector Screen Size Calculator works out all remaining dimensions in both centimetters and inches. Perfect for planning a home theater or office projection setup, you get diagonal, width, height, and area calculated automatically from whichever measurement you already know. Also try the PPI Calculator (Pixels per Inch).

Select a standard aspect ratio or choose Custom to enter your own.

Horizontal part of your custom aspect ratio.

Vertical part of your custom aspect ratio.

Which measurement do you already know?

in

Enter the known measurement in inches. Centimeters will be shown in results.

Throw ratio = throw distance ÷ screen width. Check your projector's manual. Typical: 1.0–2.0.

Results

Screen Diagonal

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Diagonal (cm)

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Screen Width

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Width (cm)

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Screen Height

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Height (cm)

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Screen Area

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Throw Distance

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Throw Distance (m)

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Frequently Asked Questions

How is screen diagonal calculated from width and height?

Screen diagonal is calculated using the Pythagorean theorem: diagonal = √(width² + height²). For a 16:9 screen that is 87.27 inches wide and 49.09 inches tall, the diagonal works out to 100 inches. This is the standard method used across all screen size calculators. See also our Phone Battery Life Calculator.

What does aspect ratio mean for a projector screen?

Aspect ratio is the proportional relationship between a screen's width and its height, expressed as width:height. The most common aspect ratio today is 16:9, used for HD and 4K content. Older projectors and presentations often used 4:3. Choosing the wrong aspect ratio can result in black bars or cropped content on your screen.

What is a throw ratio and how do I use it?

Throw ratio is the distance between the projector and the screen divided by the screen's width (throw distance ÷ screen width). A throw ratio of 1.5 means the projector must be 1.5× the screen width away from the screen. Check your projector's specification sheet for its throw ratio, which is typically between 1.0 and 2.0 for standard projectors and under 0.5 for ultra-short-throw models.

How big should my projector screen be for my room?

A general rule of thumb is that the ideal viewing distance is approximately 1.5 to 2.5 times the screen's diagonal. So for a 100-inch screen, viewers should sit roughly 12–21 feet away. You should also make sure your projector's throw distance fits comfortably within your room's length.

What is the difference between 16:9 and 16:10 aspect ratio?

16:9 is the standard widescreen format for HD and 4K TVs, Blu-ray, and streaming content. 16:10 is slightly taller and is common in computer monitors and some business projectors. For home theater use, 16:9 is almost always the better choice. For presentations and desktop mirroring, 16:10 may match your laptop screen better.

How do I convert screen size from inches to centimeters?

Simply multiply the inch measurement by 2.54. For example, a 100-inch diagonal screen equals 254 cm. Width and height follow the same conversion: multiply any inch dimension by 2.54 to get centimeters.

Does screen size refer to the diagonal measurement?

Yes — when manufacturers list a screen size (e.g. '100-inch screen'), they always refer to the diagonal measurement from one corner to the opposite corner. The actual usable width and height depend on the screen's aspect ratio.

Can I use this calculator for both projector screens and TVs?

Absolutely. The width, height, diagonal, and area calculations apply equally to TVs, monitors, projector screens, and any rectangular display. The throw distance calculation is specific to projectors — just enter 0 or leave it at default if you're sizing a TV or monitor.