What is the ANSI, Light Source, and LED Lumens?

“Wait…this projector says its brightness is 1,000 lumens while that projector says its brightness is 2,400 lumens, and they’re the same price? That doesn’t seem right, is there something I’m missing?”

A common refrain for consumers looking for their first projector is to make sure they get the brightest projector they can. But when many of these consumers actually look into the issue, they end up facing a bigger puzzle: how to make sense of the various brightness specifications listed on the market. This issue is a result of the fact that some brands on the market tend to advertise brightness specs that are different than those used by most others. Of these various brightness specs a consumer might encounter, the most common are: ANSI brightness, LED brightness, and light source brightness.

Though the standard unit used for brightness, lumens, is used by all three types of brightness, the differences in their definitions cause their values to fluctuate wildly. This results in instances where a projector using ANSI lumens might list a value of 1,000 lumens, while another competing projector using LED lumens lists a value of 2,400 lumens. The question then becomes: if all of these types of brightness are measured in lumens, why are their values so drastically different?

Suffice it to say that the reason for this inconsistency is because each of the three types referenced above measures different aspects of a projector’s brightness. But before we go further into the differences between each type (we’ll get to that later), what most consumers really need is a quick way to convert the values of one type of brightness to another, which is what the tables below are for :

Convert LED Lumen to ANSI Lumen

Convert Light Source Lumen to ANSI Lumen

*Generally, ANSI Lumens multiplied by 1.3~2.4, approximately equal to LED Lumens.

**ANSI Lumens divided by 0.04~0.06, approximately equal to Light Source Brightness Lumens

Analyzing the tables, one might notice the one constant between them: ANSI brightness. The reason why this is, is due to how each brightness measure is defined.

Based on these definitions, the reason why ANSI brightness acts as the standard for measuring brightness (as shown in the tables above) becomes more apparent. This is because ANSI brightness, as indicated in its name, is the only brightness measure which uses a standard, scientific methodology that is certified by an international body. This gives ANSI brightness measures a reliability that is not present in other brightness measures which may rely on arbitrary factors (as in how the HK effect is measured for LED brightness) or present an indirect brightness value (as in how light source brightness omits the negative effects a projector’s internal components has on its end brightness) to produce misleading/inflated numbers.