How do you calculate a Pokemon's IVs?

I know that IVs increase a stat up and one down.But how do you knowHOW MANYIVs Pokemon has? I know they have 31 possible IVs on each stat, but I have heard on Pokemon trading site people say, “There Pokemon has the max *IVs!” Also in X/Y the guy in the Pokemon station says a possible of 6 things, and will tell you what they have “Good potential.“Additionally isn’t the increase in one stat decrease in another the result of a Pokemon’s nature? Also, I read the section here, and many other Pokemon sites and I still don’t get them. Sorry for the long question I just wanted to be better at Pokemon!Thanks to everyone who answers!

Pleaselog inorregisterto add a comment.

IVs do not put a stat up and one down, that’s natures (they increase one by 10% and decrease another by 10%). Before I answer this, you need to fully understand what IVs are.

So with that in mind…

Also, some info fromBulbapediaon the IV judge and what he says:

“Incidentally, I would say its greatest potential lies in its (highest stat here).” (this is him telling you which stat has the highest IV value)

(If the Pokémon has two or more equally good best stats, then he will add one of the following lines:)“But its Attack stat is good, too.““Hmm. And its Defense stat is good, too.““Although its Sp. Atk stat is equally good.““Its Sp. Def stat seems just as good, though.““And, well, its Speed stat is good, too.”

To describe the value of the Pokémon’s highest IV(s), he will use one of the following lines:IV range of 0-15: “It has rather decent stats, I’d say. That’s how I judge it.“IV range of 16-25: “It’s definitely got some good stats. That’s how I judge it.“IV range 26-30: “This Pokémon has some fantastic stats. That’s how I judge it.“IV of 31: “Stats like those… They simply can’t be beat! That’s how I judge it.”

If you have any more questions, comment.

Use this cauculator:http://www.serebii.net/games/iv-calc.shtml