If you flop 4 to a flush your odds are 2-1 that you will make your flush on either of the next 2 streets.


This is because you have 9 outs and have 2 streets to make 1 of them.


If you don't make your flush on the turn then you still have those 9 outs but only 1 street to make them on so your odds get cut in half - now you are a 4-1 dog to make your flush.