Projector guides: What is throw ratio?


An introduction

What is throw ratio?: the most dreaded question in the world of consumer projectors. However, this doesn’t have to be the case. 

Today we’re going to debunk:

  • What it means
  • Why it’s important 
  • Working it out
  • Long vs short throw

By the end of this guide you’ll be ready to confidently setup your projector without a hitch. 

What is throw ratio?

What does it mean?

Throw ratio is undoubtedly one of the hardest aspects of projection to get your head around. In order to first understand this ratio, it’s important to understand throw distance. 

Throw distance

Throw distance is the measurement of space between the lens and the surface of the projected image. This could either be a projector screen or a wall, depending on your preference. 

There are two main results throw distance impacts:

  • Screen size
  • Screen brightness

There is a positive correlation between throw distance and screen size. Because of this, the larger the throw distance, the bigger the screen displayed; and the smaller the throw distance, the smaller the screen displayed.

The cause of this: light dispersion. Standing closely to for a spotlight will cause light to focus on you at a more concentrated level. On the other hand, standing 10 foot away means light is less focused on you and the light is more dispersed. 

The same can be applied to projectors. Of course, this concludes brightness and throw distance are negatively correlated. This means that the smaller the throw distance, the brighter the screen; and vice versa. 

As with anything, there’s a goldilocks zone that both maximises screen size, whilst not compromising on brightness: The throw ratio. 

What exactly is throw ratio?

The throw ratio is the maximum distance your projector can be placed per foot of your projector screen. Because of this, it is worked out as:

Screen width x Throw ratio = Throw distance (WxR=D)

This means if your projector has a throw ratio of 2.0 and your screen is 10 feet wide, your ideal throw is 20 feet. That is, the distance between the lens of your projector and the screen should be 20 feet. This is because:

10 (W) x 2 (R) = 20 (D)

If you were to have a throw distance of larger than 20 foot, the image would become too big for the screen, start to distort and lose some of its brightness. 

Further to this, throw distances aren’t infinite. You won’t be able to place your projector 200 feet away from the screen and expect it to project a viewable image. However, maximum throw distance (regardless of screen width) will be displayed in your user manual and is dependent on the Lumen count of your projector. 

Your projector Lumen count refers to the “brightness” of your projector. 

Short throw VS Long throw

Projector throw ratio is usually a set number (unless you have a zoom lens). But if not, it’s important to have a throw ability that suits your needs. 

There’s no point having a long throw projector in a small room, your ideal ratio is unlikely to be met. That’s why it’s incredibly important to understand how you want to mount your projector, your screen width and your ideal throw ratio, before making a purchase decision. 

In general, most projectors come with a throw of between 0.4 – 2.0, with the most common projector sitting at 1.2 with 20% zoom. 

Having zoom range on your lens allows the projector to enlarge the image displayed. This is incredibly handy for utilising your space whilst steel meeting your ideal ratio. 

Throw ratio: a conclusion

Throw ratio is a pretty daunting phrase to expect new consumers to understand. However, it’s not complex to understand once you break down the components of the calculation. 

Although you’ve now got your head around throw ratio, perhaps there are other aspects you didn’t quite understand like:

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