When you're unfortunate enough to find yourself with a short stack in an MTT (ten big blinds or less), you need to make a move and make it soon. There are some players who advocate pushing all-in any time you are first to act, and while there is some merit to that argument, if you take the time to think through situations you'll find yourself surviving – and doubling up – more often. The approach I advocate is to weigh up position and stack size before shoving, as there are varying levels of short stacks, even when you are under ten big blinds. Let’s look at a few common situations.
1. Less than four big blinds.
Even though this amount would be big enough to make people fold as a preflop raise, the fact that you don't have any additional chips makes it easier to call. Your opponents know they are going to see a showdown at no further cost, whereas if you had more chips they’d face the probability of further action on the flop and beyond. Therefore, any time you have less than four big blinds the likelihood is you are going to get called. However, you don't have the luxury of waiting. You MUST move all-in before the blinds hit you again. If you are first to act, there should be very few hands you fold.
2. Five to seven big blinds.
A typical opening raise is 2.5-4 big blinds, so you’d think having 5-7 big blinds would give you some fold equity. Unfortunately there's something about a short stack that compels people to make marginal calls. That said, you do have a little more leeway and you can probably afford to go through the blinds at least once if there is no good situation, but you should be looking for any excuse to get your chips in. In early position, shove with any pair and any two cards Ten or above. I don't like shoving with any Ace or King because hands that call you are a lot more likely to have you dominated. In middle position, add suited connectors and medium Aces like A-9, A-8 and A-7. In later position, widen the range to any Ace or King.
3. Eight to ten big blinds.
My all-in or fold threshold is ten big blinds. People are a little more hesitant to call raises of this amount, especially in the later stages of a tournament because it is usually a good portion of their stack. Believe it or not, with this many chips I actually advocate raising with more hands than you would with a smaller stack. Why? Because as mentioned above, people are more likely to fold, thus your chances of getting called and losing decrease. I'd still play relatively tight in early position, with hands like pairs, A-7 and above, and any two cards above Ten. But after middle position, I'd open the range to include most hands that have some showdown value, like suited connectors, non-suited connectors, pairs, Aces, Kings and any two big cards.