Calculating PE ratios
For just about any company whose stock is in the S&P 500, use the following calculations to determine the forward P/E ratio:
1) Pick your Favorite number between 1-9
2) Multiply by 3 then
3) Add 3, then again Multiply by 3
4) You'll get a 2 or 3 digit number...
5) Add the digits together - this is your forward Price to Earnings ratio.
Fascinating, isn't it? This is how the average P/E ratio for the S&P 500 is determined! (all you have to do is adjust the earnings estimates to fit)