Estimating LED Effficiency

[elizabeth]

How do you guess estimate the efficiency of a red LED by percentage? Where do figures like, "assuming 20% efficiency" come from?

 

[(*steve*)]

It's a rule of thumb

 

[elizabeth]

It's a rule of thumb

Hi Steve,
Is there a range? I read on another site that even the cheap stuff should be about 30% efficient.

Thanks,

Elizabeth

 

[(*steve*)]

I think you'll find that the difference is the difference between engineering and sales.