% of runner runner flush after flop?

[Woodsey]

Had a big cash hand at Empire earlier with lots of players all in where this made a difference to me calling off the rest of my stack on the flop or not as the pot odds were tight. It made me realise I didn't know what the % of this happening was so I could add it to my other outs, anyone know? I guessed about 6-7% at the time but I'm still not 100% sure?

eg I have  and there is 1 spade on the flop, what should I add?

[kinboshi]

It's about 4% to hit a backdraw flush, if you have two cards to come (I think).

[Woodsey]

It's about 4% to hit a backdraw flush, if you have two cards to come (I think).

Yes 2 cards to come, any advance on 4% anyone?

[Longy]

Assuming no knowledge of any other cards. There are 47 cards unknown, 10 of which are spades.

So 10/47 * 9/46= 90/2162 or 4.16%

[Woodsey]

OK ta, that info will encourage me to  a bit more

LOL I see Jakally is looking at this thread, 3   2   1 before pisstake about me being a fish

[Karabiner]

I seem to recall that the wisdom was that it was either 21/1 or 22/1 so that would concur with c4%.

[dousche]

subtract a little for the times where you're in against a set/2 pair and he fills up? then some of your outs are discounted