What is an ANSI lumen, and why does it matter?

An ANSI lumen is light output measured to a defined procedure — nine points across the image, averaged — while a plain “lumen” on a projector box is measured to nothing and can be ten times larger.

What the procedure actually is

The ANSI method divides the projected image into nine equal rectangles, measures the illuminance at the centre of each, averages them, and multiplies by the image area. Two projectors measured that way can be compared. That is the entire point of a standard.

Why the gap is so large

An unqualified figure is often the raw output of the light source before it passes through the panel, the colour wheel and the lens — the light that goes into the machine rather than the light that leaves it. A machine advertised at “20 000 lumens” and specified at 400 ANSI lumens is not necessarily lying about either number; it is quoting two different things and printing the larger one in the largest type.

How to read a listing

Look for the unit, not the number. “2 200 ANSI lumens” is a claim you can hold a maker to. “12 000 lumens” with no unit tells you the manufacturer chose not to state a measured figure, which is itself informative.

What brightness you actually need

More than most people expect in a living room with daylight, and less than most people expect in a dark room. Manufacturers of home cinema projectors quote figures in the hundreds to low thousands of ANSI lumens, and the difference between a controlled room and a bright one is the single largest factor in how much you need.

This does not replace the manufacturer's own instructions. Every brightness figure, contrast ratio, power rating and load capacity on this page is reported from the manufacturer's own documentation, with its unit written as published, and named as such — none of it is measured here. A brightness figure that is not expressed in ANSI or ISO lumens is reported as the manufacturer expressed it and is never converted, because no conversion exists.