Projector Throw Calculator
Solve projector throw distance, image width, or throw ratio from the other two, with screen-diagonal helpers.
Processed locally in your browser — nothing is uploaded.
Projector Throw Calculator
Distance ÷ image width. Check the projector spec sheet.
Results
- Throw distance
- 130.5 in (10.88 ft)
- Throw ratio
- 1.5:1
- Image width
- 87 in
- Throw distance
- 130.5 in
distance = throw ratio × image width. Zoom lenses cover a ratio range (e.g. 1.5–2.2:1); ultra-short-throw projectors are below 0.4:1 and sit right under the screen. Measure from the lens, not the projector body.
About Projector Throw Calculator
The whole relationship is distance = throw ratio × image width; give any two and the third is solved. A helper converts a screen diagonal and aspect ratio into image width, and presets cover standard (1.5–2.2:1), short (0.4–1:1), and ultra-short-throw (<0.4:1) lenses.
Common uses
- Check whether a projector fits your room before buying
- Find the mounting distance for a chosen screen size
- Work out what screen size an existing mount position produces
Example
Input
Throw ratio 1.5:1 · 100" wide image
Output
150" (12.5 ft) throw distance
Limitations
- Zoom lenses span a ratio range — compute both ends. Measure from the lens; offset and lens shift are not modeled.
Frequently asked questions
What does throw ratio mean on a projector?
Throw ratio is the throw distance divided by the image width. A 1.5:1 lens needs 1.5 feet of distance for every foot of picture width, so the whole geometry reduces to distance = ratio × width.
How far back does a projector need to be for a 100-inch screen?
A 100-inch 16:9 diagonal is about 87 inches wide, so a standard 1.5:1 lens needs roughly 131 inches — just under 11 feet. The diagonal helper does the aspect-ratio conversion for you.
What counts as an ultra-short-throw projector?
Lenses with a throw ratio under about 0.4:1, which can paint a 100-inch image from just inches off the wall. Short-throw sits between roughly 0.4:1 and 1:1, and standard lenses run about 1.5:1 to 2.2:1.
Does this calculator transmit my room measurements?
No. Every throw calculation happens in your browser and your distances and screen sizes are never sent anywhere or saved.
Do I measure throw distance from the lens or the front of the projector?
From the lens, since throw ratios are specified lens-to-screen. If your projector has a zoom lens, run the calculation at both ends of its published ratio range to get the usable mounting window.