after giving the odds and outs articles some thought i dont really understand how the odds (not pot odds but card odds) are calculated

looking at the sample flushdraw

hand Ah9h

flop 2h6hKs

there are still 47 unknown cards, of which 9 are hearts

the probability of getting a good card (heart) is - good / possible so 9/47 which is ~19%

if you didnt hit at the turn the probability of hitting a heart on the river is 9/46 which is again roughly 19%

seeing the flop we can say that the probability of hitting our flush on the turn or river is

1 - [1 - (9/47)] * [1 - (9/46)] = 34.9%

now ok, but the odds, how did you calculate these? the table states

Flushdraw : Odds from flop to river (2 cards) = 2:1

is that an approximation of the probability of hitting your flush on the turn or river (34.9%) + taking into consideration the possibility of hitting a 3 of a king, 2 pair, full house and using some thumb rule rounding that up to 50%

or how do you actually come up with odds?

anyway, thats the first thing (how do you come up with odds?)

the second is, i was wondering if you could somehow simply skip the odds and focus on your outs and pot odds because in not straight forward situations you only have outs and no odds

seeing as odds anyway always are like <50% better then the odds probability of improving (like flushdraw says 2:1 on turn+river while the outs probability is more like 35%)

can you take this as a thumb rule? flop to river it would be * 1.5 and flop to turn like * 1.3