how to perform a two card (turn and river) calculation

i know it is rare to have to do this in real situations, but still necessary. how do you do it with
1. percentages
2. ratios
?

A quick way of working out your percentages is -
count how many outs you have,
then for the tun & river multiply by 4
and for the river multiply by 2.

This is not exact science but a quick way of giving you a rough idea on your chances.

So, if I have 8 outs after the flop, I would have a 32% of hitting or roughly 3 to 1 against hitting one of them and on the river I would have a 16% chance of hitting, or roughly 5 to 1 against hitting? Am I even close?
LOL

ya you're close, but that's only a rough estimation. i was hoping more for exact calculations

That method is pretty good. Add a percentage point and it's usually closer.

IE, if you have three outs on the turn, 3 x 4 is 12, so you have about a 13% chance.

There are so many other variables to the game, that being off by a percentage point or two when calculating outs isn't that important.

For best results after the flop you need to take into account the number of cards that will leave you drawing dead on the river.

^^^ Very helpful if you can see the other guy's hole cards.
Otherwise...

you also have to take into account whether it's a 6 9 or 10 seat table, ie. how many cards are left in the deck? also pot odds and the implied odds.

you only use a two card calculation when someone else went all in, and you are deciding whether or not to call. therefore, implied odds do not come into play.

no one has still said how to figure out the ratio odds, only the percentage

In an all in situation you are correct, the Q is a tad obscure.

why do you ask about knowing both ratio and precentage? Diff. way of saying same thing. Is this for knowing if you have pot odds to call all in? (I've just been downgraded from expert to regular member) What I do is estimate % of making my hand and then multiply that by total pot if I call. If the result is greater than what I have to call I have pot odds. Pots 30 bet is 50 pot will be 130 i'm 36% to win...0.36x130=47. i will win 47 on avg have to call 50 less than even money play I fold. this is for easy flush draw vs pair situation, if you think you're up against bigger hand, you have more to work out. Use a poker calculator to work out % of usual flop situations so you already know the numbers.

Pothole, it doesn't matter the # of plyrs unless you know what they had. All dead cards are part of the "deck" as far as we're concerned. Carrico, I think changing to a ratio just confuses the matter. Although in limit games with incremental bets I would use ratios and fractions only (32% is 2 to 1 not 3 to 1 against)

2-4 rule is close enough unless you have a ton of outs. I think something closer is subtracting 1 for every out over 8? if you want exact it will be outs/47 for the turn and outs/46 for the river although this is not needed if it is within a percentage other factors come into play. A poker caluculator can easily be found and I beleive there is one on here as well. It might be a good idea to mess around with some common combinations for good reference points.

Uh... what do you mean radio odds? Like being 50% to win being a 1/1 ratio?

i always use ratios to figure out whether or not i have the pot odds to call. on the flop, if i have 10 outs, i would calculate the ratio of me getting an out to not by (47-10)/10, therefore 4.7:1. the pot will need to be 4.7 times bigger than what i need to call with. that's a one card calculation. how can i do that for two cards in a row?

I'm new at calculating my own odds myself, but I would agree with D'wilius about confusing the issue with ratio. Whether you calculate odds as percentage or ratio makes no difference, because both are interchangeable and easily converted as long as you remember the "add one" rule, i.e. 1:4 = 1/5 = 20%, not 25%. Also it's probably a typo but your calculation of (47-10)/10 = 4.7:1 is incorrect. It would be 3.7:1, or 1/4.7 = 21.3%, so your call would need to be no more than ~21% of the pot to get proper odds.

At least I think that's right, I'm still a noob at this.

I like to use cardplayer.com as a good example guage.. its an easy way to check your math against the what it really is. Its under tools and tips.. and yeah Im sure that most of you know about it already but I was excited to learn it was there.