It's no secret that Warzones give XP in Swtor but the real question is how much XP do they give? Believe it or not leveling by just doing Warzones is actually a possible and viable alternative to just questing non stop. Also not only do you get XP for every Warzone win and lose you also get credits and commendations. The commendations I will go into detail explaining later in another guide so for now let's focus on the experience and credits.
You won't be getting XP for killing people in Warzones or completing objectives but you will get a large lump sum of XP and credits after every match regardless of if you win or lose. Of course you will receive more XP and credits if you win a match rather than losing but as far as I know the amount of XP and credits you receive is in no way tied to your performance during that Warzone. I've spent an entire match guarding a turret in The Civil War and still got close to the same amount of XP I got from a previous game where I ran around and ripped people's heads off.
Since players of all levels are allowed into all Warzones with other players of all levels (you have to be level 10 at first to enter, of course) the amount of XP and credits you receive per win scales with your level. From my experience leveling in Warzones a win nets you about half to 3/4 of a bubble and a lose, depending on how your team did, will give you anywhere from a fraction of a bubble or a quarter of a bubble.
To kind of show you the amount of XP you will be getting for each win and lose I decided to take a few screenshots on my level 39 Jedi Shadow at the end of each Warzone I did. You'll be able to see that the results vary from game to game but still hold a general amount of how much XP you should be expecting to make for each Warzone. First, let's take a look at all of my victories...
Again, all of these pictures were taken when I was level 39. If you need help seeing one of the pictures, just click on it to enlarge it.
As you can see the XP from winning is more than it is from losing, but losing still isn't that bad of XP. In order to go from level 39 to 40 it takes 303k XP, just incase you wanted that number to do the math to see how many Warzones it would take winning and how many losing.
If you're interested in doing lots of PvP to level up then I strongly recommend you read some of my guides so you know exactly what to expect in each of these Warzones. Going into them knowing what to expect instead of blindly will help you out tons. Not only that biut it will help out your team, and if you and your team win you're looking at 3x the amount of XP you would have gotten if you lost.