Lumens, candelas & equivalent LEDs

[hl_world]

I'm trying to determine the millicandela rating of an LED from a keychain to find equivalent LEDs of different colours. The keychain LED specs are as follows:

Luminous Flux value: 4 lumens (from box)
Viewing Angle: 30° (I got this value by comparing to LEDs with marked angles)
Wavelength: 650nm, maybe shorter (again from comparison)
Diameter: 5mm

Now I used http://led.linear1.org/lumen.wiz to get the millicandela rating but it seems to take a value of ~19000 millicandelas at 30° to get ~4 lumens but it only seems as bright as one of my loose LEDs (10000 mcd, 20°, 630nm). Admittedly, I held it a little further back but when both spot sizes were equal, so was the brightness. Does this seem right?

 

[Valerie Park]

The answer to your question is that it depends. The millicandela rating of an LED is determined by the amount of light it emits in a particular direction and at a particular wavelength. The millicandela rating can vary depending on the angle of view, wavelength, and size of the LED. It is possible that the LED on your keychain has a higher millicandela rating than the loose LED you are comparing it to. In order to get an accurate comparison, you would need to measure the millicandela rating of both LEDs.

 

[sir-pinski]

Based on the information provided, it does seem like the keychain LED has a lower millicandela rating than the loose LED with similar specifications. However, it is important to note that the millicandela rating is not the only factor that determines the brightness of an LED. The viewing angle, wavelength, and distance from the light source also play a role in perceived brightness. It is possible that the keychain LED has a wider viewing angle and a different wavelength, which could affect how bright it appears compared to the loose LED. Additionally, the accuracy of the website's calculation may also be a factor. It is always best to test the LEDs in person to get a more accurate comparison.