What Is Throw Ratio? (Projector Buying Guide)
Throw ratio is the spec that decides whether a projector can physically work in your room — and it’s routinely ignored until the return window. Two minutes here saves that mistake. No jargon, one formula, real examples.
The definition
Throw ratio is the distance from projector to screen divided by the width of the image it produces. A ratio of 1.5:1 means the projector needs 1.5 metres of distance for every 1 metre of picture width. Bigger ratio = sits farther back; smaller ratio = sits closer.
The three families
|
Family |
Ratio |
Sits (for 100" image) |
Typical use |
|
Standard throw |
above ~1.0 |
3–5 m back |
Living rooms, theatres |
|
Short throw |
~0.4–1.0 |
about 1–1.5 m |
Small rooms, classrooms |
|
Ultra-short throw |
below ~0.4 |
centimetres, on furniture |
TV-stand setups, interactive walls |
Zoom lenses give a range (say 1.32–2.15:1), which is placement flexibility; fixed lenses give one number. Neither is better — the range just forgives imperfect rooms.
How to use it (the only math you need)
Distance = throw ratio × image width. Want a 100-inch picture (≈ 2.2 m wide) from a projector with a 1.5:1 ratio? You need ≈ 3.3 m. Only have 1.1 m? You need a ratio of 1.1 ÷ 2.2 = 0.5 — a short-throw projector, and no standard-throw model will fix that with wishful thinking. Our How to Measure Throw Distance guide turns this into a full room-measuring routine.
Why you shouldn’t “fix it” digitally
Digital zoom and heavy keystone correction rescue bad placement by discarding pixels and brightness — you paid for both. Match the ratio to the room and the whole image reaches the screen.
Frequently asked questions
What does a throw ratio of 1.5 mean?
The projector must sit 1.5 units back for every 1 unit of image width — about 3.3 m for a 100-inch (2.2 m-wide) picture.
What throw ratio do I need for a small room?
Divide your available distance by your desired image width. Under ~1.0 means short throw; under ~0.4 means ultra-short throw.
Is a lower throw ratio better?
Only if your room demands it — short-throw optics cost more at the same picture quality. Buy the ratio your room needs, not the smallest number.
The bottom line
One division — distance ÷ width — sorts every projector into “fits my room” or “doesn’t.” Every product page in our Epson and Dangbei collections lists throw specs, and the measuring guide takes it from here.
Sources
[1] Throw ratio definition and calculator — Projector Central.
[2] Manufacturer throw specifications — epson.ca, us.dangbei.com.
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