Finding Lux for an LED array--Is this correct?

Discussion in 'The Projects Forum' started by LEDwire, Mar 11, 2015.

  1. LEDwire

    Thread Starter New Member

    Mar 1, 2015

    I wanted to know if I'm calculating the lux of my LED array correctly and thought this would be a good place to ask.

    The LEDs I'm going to be are 3W with 240 lm per LED, with a 60 degree viewing angle.

    I was using the calculator from this site:
    240 lm with 60 degree viewing angle = 285.11 cd,
    285.11 cd at a distance of 1 meter ~285 lux at 1 meter.

    Is this correct? Am I misapplying these calculators?

    I'm making a SAD therapy light with a user distance of 1 meter. Therapeutic levels of light for SAD are 5,000 to 10,000 lux.

    So when I plug in my numbers, it comes back that I need only (10,000/285) about 35 LEDs for this project. It would seem like I'd need more than this.

    Just wanted to check my "math" and numbers.

    Thanks for any help.
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    Looks correct to me..

    Assuming you want 10,000 lux I'd add extra LEDs to account for the fact that you more than likely will not (shouldn't) be driving them at their max rating.
    I'd also use dimmable drivers to light levels can be tailored..

    Or I'd just look out the window :)... Sorry.. Don't believe in that kind of stuff..