Are implied odds a large factor in deciding whether to call a raise in NL?

Is the implied odds calculation always: current bet vs villains stack?

How does and should this work?

yes ldo

no

it works by trying to work out if we can potentially win enough from villain in future streets to make what's a bad call looking at purely direct odds ok

Yes, implied odds does play a roll, but it varies from situation to situation. Stack sizes play a big roll, but other factors do as well.

First, how hidden your draw is play a major roll. For example, certain straight draws are very hidden and villain won't be certain you made a straight in certain situations whereas flush draws aren't nearly as hidden.

Secondly, how big of a hand you put villain on. The stronger villain's hand, the more likely you are to get paid off with your implied odds if you make your hand.

Both points work together to help you make your decision.

Except when you or another player is all in, implied odds are always in existence. No limit holdem is built on implied odds (and also the implied threat of a big bet), since there's the potential for someone to get their whole stack in at any moment.

You can do calculations based on the maximum possible winnings (by adding pot + effective stack) but the implied part is not an exact science. Along with the ideas hardin mentioned above, I'd add that knowing your villain is also crucial. Some players (mostly weak tight nits) will never pay you off when a flush comes in, whilst others feel it is their duty to pay you off. So with precisely the same hands and boards, your implied odds might be high against one player, but low against another.