Y can't I re-raise?

I've wondered about this 4 years but never asked about it. lets say 4 example that there are 3 ppl in the hand. lets say i raise 1000 chips, the 2nd guy calls, & the 3rd person goes all in w/ his last 1200 chips, basically re-raising me 200 more chips. but then i'm only given the option 2 call, not raise. if he raised, y can't i re-raise? is it cuz his raise wasn't at least the size of my raise? or not at least the size of the bb?

Yes, because you already made your bet, a second raise is not "opened" to you unless the raise from that guy is a certain percentage.

I don't remember how much exactly is needed and that could vary among sites?

In No Limit Hold'em, the raise amount must be at least as much as the previous bet or raise in the same round. As an example, if the first player to act bets $5 then the second player must raise a minimum of $5 (total bet of $10).

If someone goes all in, and that raise doesn't meet the above requirements, then the betting has not been opened again, and you can only call.

thanks guys!

It's called an under-raise, if he had raised a standard raise amount, you could re-raise. Sometimes, especially in micro tournaments you can be pretty sure that a small stack will re-raise you if he's just lost a huge chunk of his stack last hand, so say he has 800 chips left, at 200 blinds, raise to 400 if you had say AA, he will shove, a ton of people may call and you can isolate him and pick up a ton of dead money. I've used this a few times, but it's a rare spot, and obviously sometimes, you find a shortstack who doesn't tilt, and your move fails, but when it works, it's a nice spot.

This just happened like 10 mins ago..
Example: This person just lost a big hand previously...

View hand 1193197
DeucesCracked Poker Videos Hand History Converter

BB: t920 9.20 BBs
UTG: t4500 45 BBs
UTG+1: t1145 11.45 BBs
MP1: t6060 60.60 BBs
MP2: t855 8.55 BBs
Hero (CO): t1395 13.95 BBs
BTN: t4895 48.95 BBs
SB: t2735 27.35 BBs

Pre Flop: (t150) Hero is CO with A A
UTG calls t100, 3 folds, Hero raises to t200, BTN calls t200, 1 fold, BB raises to t920 all in, 1 fold, Hero raises to t1395 all in, 1 fold

Flop: (t2190) Q A J (2 players - 2 are all in)

Turn: (t2190) 7 (2 players - 2 are all in)

River: (t2190) 6 (2 players - 2 are all in)

Final Pot: t2190
BB shows Td Jd (a pair of Jacks)
Hero shows Ac As (three of a kind, Aces)
Hero wins t2190

Lol, I wondered the same thing and am glad to have a logical answer. Like it or not, I guess it makes sense.

In my experience, Casinos in the UK all follow the rule that you cannot use an under-raise (an all-in raise less than the correct amount) to launch a further raise.

Note though, that if UTG raises to 1000 and MP1under-raises to 1100, MP2 can still Re-Raise to any amount because he's launching the raise from the UTG's full (normal) raise. My exact wording is supect here but I'm sure you get the idea. :-)

I have also seen the rule (can't remember where) that if Player 1 bets 1000 and Player 2 under-raises all-in to 1200, then any caller has to call the full amount of what the raise should have been - i.e. 2000 but I don't think this is very common.

Steve