how can i find historical FTSE 100 p/e ratios?

Answer 1

I recommend you calculate them yourself..

p/e ratio is Price divided by Earnings.

But share prices change EVERY DAY ...
(and Earnings change every time the Company declares it's results - typically twice a year but some quarterly ...)

SO - for any specific day in the past you need to know the average (or closing, if you prefer) Share price that day and the last declared Earnings.

Answer 2

you will possibly be able to desire to've calculated it your self via doing earnings divided via all the fees xD - that could be on the time. i think of, google finance use earnings Predictions/present day cost on their P/E. yet do not quote me on that.