Calculating the pot odds

[gamblinghammers]

I play texas holdem quite a bit but still struggle calculating the combined odds. eg If I had 2hearts in my hand and another two come on the flop I realise I have the following chances of making a flush: Turn Card 9/47 = 19% River 9/46 = 19.5% How do I work out the overall % of making a flush? I never was any good at probability. Also could anybody tell me of a web site that list all these odds for free? Cheers for any replies.

[Jonny1723]