Understanding Projector Throw Ratio – Lightform Guide

Lightform devices work with most projectors —

LFC Kit: Your projector's throw ratio should be in the range of 0.50-2.0

LF1: Your projector’s throw ratio should be in the range of 0.85-1.8

Glossary

Throw Ratio

The relation between the throw distance and the image width; tells us what image size we can project from a certain distance away.

Throw Distance

The distance between the projector's lens and the projected image.

Image Width

The width of the projected image.

What’s a throw ratio?!

^ For projectors compatible with LFC

Throw ratio is the relation between the throw distance (the distance between the projector's lens and the projected image) and the width of the projected image:

Throw Ratio = Throw Distance / Image Width

Throw Ratio tells us what image size we can project from a certain distance away. For instance, a throw ratio of 1.5 indicates that for every 1 foot of image width, the throw distance must be 1.5 feet. The smaller the throw ratio, the larger the image a projector will produce at a shorter throw distance.

Note: Throughout this article, we refer to throw ratio in terms of horizontal throw ratio, in which the throw ratio is described as the throw distance compared to the image width. Sometimes, the throw ratio is measured in terms of throw distance to image height (vertical throw ratio) or image diagonal (diagonal throw ratio).

Using Throw Ratio

Using the throw ratio equation and its variations is essential when selecting the right projector for your experience — it’s important to consider the positioning of your projector and the size of the image you’d like to project (or the size of the scene you’d like to cover). With the throw ratio equation, you can determine:

The ideal throw ratio given the setup of your experience
TR = TD / IW
(Throw Ratio = Throw Distance / Image Width)
Where to place a projector given its throw ratio & your projected image size
TD = TR x IW
(Throw Distance = Throw Ratio x Image Width)
The width of the image a projector will produce given its throw ratio & throw distance
IW = TD / TR
(Image Width = Throw Distance / Throw Ratio)

Calculation Examples

Calculating the optimal throw ratio for your set up
TR = TD / IW

e.g., If you want to project an image that is 20ft wide while placing your projector 30ft away, you will need a projector with a throw ratio of 1.5 (30ft / 20ft).

Since the LF1 supports throw ratios of 0.82-1.77, in this example, you could also use a projector with a throw ratio of 0.9 from 18ft away (18ft / 20ft) or a projector with a throw ratio 1.75 from 35ft away (35ft/20ft) to also achieve a 20ft wide image.
Calculating where to place your projector
TD = TR x IW

e.g., If you want to project an image that is 20ft wide using a projector with a throw ratio of 1.5, you will need to place the projector 30ft (20ft x 1.5TR) away.
Calculating how wide of an image you will project
IW = TD / TR

e.g., If you have a projector with a throw ratio of 1.5 and place it 30ft away, you will get an image width of 20ft (30ft / 1.5TR).

Understanding throw ratio helps with selecting a projector that is suitable for your experience. The LF1 works best with throw ratios between 0.82-1.77. Keep in mind your environment setup, any installation limitations, and your potential projected image size.

Tip: Check out Epson's web-based distance calculator tool and the accompanying video.