how to tell the brightness of leds

I want to learn about the brightness of leds and don't know where to go to find that information. Does anyone here know how to tell the different or how bright an led is?

thanks

Ron

You will need to look up the specs for the particular LED. LEDs are rated in millicandela (mcd), which is the unit of luminous intensity. You have to be careful when you talk about the luminous intensity of an LED though. A millicandela is frequency specific, so two LEDs rated the same mcd but different color will perceived as different brightnesses. The radiation angle of a particular LED with also affect the perceived brightness of an LED. There are formulas that you can use to determine relative brightness. To compare two different LEDs, it is probably best to compare their luminous flux or lumens. This unit takes into account the luminous intensity and radiation angle.This information is provided only as a reference.

All circuits should be verified with a digital multi-meter prior to making any connections.