Draws, outs and equity question...

[DFb3]

Is there a chart or simple formula somewhere to determine how to convert outs to pot equity percentage?

For example.. 8 outs "as I understand it" is about 32% pot equity. So you would have a pot equit edge with 4 opponents but not with 2. How do I arrive at this 32% figure based on 8 outs? I want to be able to figure it out for other outs as well.

Is there a formula that I should be using or is there a chart somewhere that I should just memorize for 1-12 outs? Is it the difference between the flop to turn and turn to river ratios? (4.75 to 1, and 2.2 to 1)?

[MathEconomist]

Pot equity is just your chance of winning the pot. So the 8 outs being about 32% is the chance that one of the 8 outs will hit by the river. This is why you might, for example, sometimes raise with a flush draw on the flop in limit HE against 3 or 4 opponents. Because the pot is large enough that you'll be in until the river and you have about a 1/3 chance of winning but are getting 3-1 or 4-1 on your money.

You can calculate the chance of completing your draw on the flop as 1-(47-outs/47)(46-outs/46) (in other words, 1-P(miss on both streets)). Or you can just look them all up and memorize them. IIRC Holdem for Advanced players has a chart at the end or you can google one. Three big caveats:
1) Your chance of completing the draw is not necessarily your chance of winning the hand. Sometimes you make your draw and lose anyway. So you may have to be careful in some situations.
2) Unless everyone is all-in on the flop, you are only getting one card for whatever price you're getting. This is especially important in NLHE, since calling a pot sized bet with a flush draw on the flop may seem correct (2-1 on your money and slightly better than 2-1 to hit by the river), but you'll have to call another bet on the turn which means you're actually paying something closer to 1-1 to see the river.
3) Having an equity advantage doesn't automatically mean raise. Say I flop the nut flush draw with no pair on the board and there are 4 others who took the flop. If the player immediately to my right bets, I (probably)shouldn't raise even though I have and equity advantage over 4 players because if I do they might fold leaving me heads up and killing my edge.