Lux vs lumens
Projectors advertised in lux are quoting illuminance at an unstated distance, not output. Convert lux to lumens for your screen size, with a computed table.
Lumens measure the total light a projector puts out; lux measures how brightly that light lands on a surface, and it falls off as the image gets bigger. A “9500 lux” claim is illuminance at some small, unstated distance — it is not comparable to a lumen figure. To convert: lumens = lux × screen area in square metres. On a 100-inch screen (2.76 m²), even a genuine 3 000-lumen projector delivers only about 1 090 lux.
The two units answer different questions. Lumens describe the projector; lux describe a particular spot on a particular screen at a particular size. Because a bigger image spreads the same light over more area, lux drops as you zoom out — which is why a lux number without a stated screen size or distance tells you nothing. Sellers quoting four- and five-digit lux figures are usually measuring inches from the lens. Do the conversion yourself: divide the claimed lux by the lux the table below shows for your screen, and you get the lumens implied.
What a projector's brightness gives you, in lux
| Screen | Screen area | 1 000 lm gives | 2 000 lm gives | 3 000 lm gives |
|---|---|---|---|---|
| 60″ | 0.99 m² | 1010 lx | 2015 lx | 3025 lx |
| 80″ | 1.76 m² | 565 lx | 1135 lx | 1700 lx |
| 100″ | 2.76 m² | 365 lx | 725 lx | 1090 lx |
| 120″ | 3.97 m² | 250 lx | 505 lx | 755 lx |
| 150″ | 6.20 m² | 160 lx | 320 lx | 485 lx |
Frequently asked questions
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