Throw distance = throw ratio × screen width. A projector with a 1.5 throw ratio needs 15 feet of distance to fill a 10-foot-wide screen. Every 4K laser projector's spec sheet lists a throw ratio (sometimes a single number, sometimes a zoom range like 1.2 to 1.6), use it below with your screen size or your available room depth.
Calculate
Assumes a 16:9 screen. Throw ratio ranges above are typical for each projector class, not a guarantee, always check the specific model's own spec sheet for its exact ratio before mounting anything permanently.
Typical throw ratios by projector type
| Type | Throw ratio | Distance for a 100" screen | Typical placement |
|---|---|---|---|
| Ultra short throw | 0.19-0.42 | 1.4-3.1 ft | Low console, inches from the wall |
| Short throw | 0.38-1.0 | 2.8-7.3 ft | Coffee table or shelf, a few feet back |
| Standard throw | 1.1-2.2 | 8.0-16.0 ft | Ceiling mount or back of a mid-size room |
See how these three categories compare beyond just placement in ultra short throw vs. short throw vs. standard throw.
Worked example
Say a room has 12 feet of usable depth and the projector is a standard throw model with a 1.2-1.5 throw ratio. Switch to "Screen size, from my available distance" above, enter 12 feet, and the calculator returns the screen size range that fits without the projector needing to sit past the couch. Going the other way, entering a target screen size tells you the minimum room depth to shop for before buying.
Frequently asked questions
What is projector throw distance?
How far a projector needs to sit from the screen to fill it exactly, calculated as throw ratio times screen width.
What is a throw ratio?
A projector's distance-to-width ratio, published in its spec sheet. Some projectors have a single fixed ratio, others have a zoom lens with a min/max range, giving some flexibility in exact placement.
Does throw ratio change with screen size?
No, throw ratio is a fixed property of the projector's lens. It scales proportionally, a 1.5 ratio projector always needs 1.5 feet of distance per foot of screen width, whether the screen is 80 inches or 150 inches.