mcd to lumen calculator....wanted

Hi All,
I'm after a simple, free download for converting datasheet values of mcd to lumens for rough comparisons between LEDs in LED array design.
I know of an online one here:
led.linear1.org/lumen.wiz
and I've got the spreadsheet from here:
http://candlepowerforums.com/vb/showthread.php?t=118485
(Yep..I know a proper calculation needs to be integrated over the whole beam pattern, but I'm just doing relative comparisons...an estimate based on the 1/2 intensity beam angle would be OK)

All very good, but a little unwieldly. Does anyone know of a nice simple converter/guestimater, preferably something for the Palm series...but PC download would be OK.
Thanks
Phil

You can't convert mcd to lumen--as someone in the other thread said, it's like converting mpg to horsepower. Knowing the 1/2 intensity beam angle doesn't help much. You need to know how the energy is distributed both within that angle and outside of it.

You can convert from mcd to lumens (with huge margins of error!) if you have at least peak beam candlepower and a beam angle. Beware that beam angles are typically calculated to the 50% relative intensity point - typically resulting in undervaluing narrower beam angles.

I assume you've looked at my rather complex beam geometry analysis spreadsheet since you linked to the most recent thread I mentioned it in? You could use the source spreadsheet for the LED DB in my signature, but beware that it's tremendously inaccurate.

Hi,
Thanks for the link to the DB spreadsheet. It will help in comparative analysis to have typical LED lm output.
FYI the LEDs will eventually be potted in clear resin (hence looking at lm not mcd as any optics will be voided).
Phil