Projector Throw Distance Calculator

Enter the projector’s throw ratio and the screen size.

By TheCalcTools Updated October 17, 2026 Formula checked and tested

Your numbers

Throw ratio (distance ÷ image width)

Printed in the projector's specifications, often as a range for zoom lenses

Image diagonal

Aspect ratio

Or: distance available

Throw distance for this image (ft)

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In metres

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Image width (in)

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Image diagonal at the distance you have (in)

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Throw ratio = distance from the lens to the screen ÷ image width. Multiply the image width by the throw ratio to find the distance.

Short-throw projectors have ratios below about 1; ultra-short-throw below 0.4. Zoom lenses give a range, so check both ends.

Distance = throw ratio × image width

Using the default values shown in the calculator:

Throw ratio (distance ÷ image width)	1.5
Image diagonal (in)	100
Aspect ratio	16:9
Or: distance available (ft)	10

A 100 in 16:9 image is 87.2 in wide, so a 1.5 throw ratio needs 10.89 ft (3.32 m).

Result:

Throw distance for this image (ft)	10.89
In metres	3.32
Image width (in)	87.2
Image diagonal at the distance you have (in)	91.8

How far for a 100-inch screen?

With a 1.5 throw ratio and 16:9, about 10.9 ft (3.3 m).

This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.