I want to convert cpm (cost per 1,000) rates for advertising on-line
to cpa (cost per action) are there any (besides just cpm) mathematical
formulas for use in on-line media planning ? I need to know the actual
mathematical formulas not just a link to a calculator.

HI,

the formula is :  CPA = (CPM * (impressions/1000)) /(#of sales);

if you want more explanation say me.

hope this helps.  ;-)

Ok CPA = (CPM * (impressions/1000)) /(#of sales);

This is assuming I already know the cpm - what if the very thing I am
trying to do is convert a COST PER LEAD (CPL) into what it might be as
a CPM in other words in the case where I bought 150 leads @ a 10 CPL
over one month what would my CPM be ? Also before I start a ad
campaign and I have no stats yet what data should I have to know this.
 Is the best practice here to do a test run for a month and then
figure a cpm. I need to be able to convert back and forth from CPL to
CPM. Can you give me a simple example ?