When discussing the choice of tournament, the presence of recreational players and the guaranteed size of the prize pool are most often mentioned. The total number of participants is usually given less attention, but this metric is the most important when choosing a game and even significantly influences strategic decisions at a later stage.

First, let's define a large field. This is a very relative concept. 500 people isn't that much for a World Series bracelet event or $11 online tournament. But in a super high roller tournament or in an ordinary tournament at a local casino, even 100 people is very decent. In this article, I will consider small fields with 150 or fewer participants and large fields with 500 or more.

If you can tell me the average size of the field in the tournaments you play, I can tell you something about your poker career. Let's look at the reasons why you might prefer small fields to large ones, or vice versa.

Advantages of small fields

Those who regularly play in small fields face a lot more difficult ICM situations. If you specialize in 100-man tournaments, you will find yourself on the bubble, final table bubble, final table, and heads-up much more often. Thanks to experience, you will get used to difficult situations much faster and will be able to make better decisions more often. However, if you're heavily loaded with 1000+ player tournaments, you'll be less likely to find yourself in the later stages and may not have enough play where you need it most. Of course, you can train with the help of simulators, but the practical experience of making expensive decisions is still much more valuable.

Another advantage of small margins is the reduced variance. This is easy to see with the Tournament Variance Calculator. Let's compare $50 tournament regulars with 10% ROI in MTTs for 100 people with 15 payouts and for 1,000 people with 150 payouts.

20 simulation options for small fields:

And the same for the big ones:

In large fields, the rises are higher, but the falls are deeper and more frequent. In small fields, we often remain in the black. In large fields, we will be in the red 40% of the time after 1,000 tournaments, and the bankroll required to play is $23,069. In small fields, the chance to play 1,000 tournaments in the red is 18%, and a much more modest bankroll is needed – only $8,742.

Let's zoom in on the best plots to see the effects of variance up close:

In small fields, the increase in winnings is stable and gradual, there are many small peaks and plateaus. Success in big fields was brought by several powerful upstreaks, between which we had to play for a long time without reaching.

Our comparison is not entirely correct, because, as we will soon see, ROI in big fields, all other things being equal, will be higher. However, the streaks inherent in poker are much easier to deal with when playing small fields. Busting out on the final table bubble doesn't hurt as much when you get to that stage regularly, but when you have to wait months for your next chance, even the toughest can break.

A professional who specializes in large fields can do everything right and lose for years. Downstreaks ruined a lot of great players and sapped the self-confidence of others who did not fully understand how large the variance in such tournaments was. It is no coincidence that deals are almost always made in the endings of large MTTs – everyone wants to reduce the variance!

All these problems are not experienced by specialists in small fields. Despite the fact that the participants of the Super High Roller tournaments play against the best players in the world, the low variance makes these events more attractive to regulars than the hard 5-20K for 600+ people.

Advantages of large fields

The main reason to play large fields is the big payouts. One big ride can set you up for a whole year, double your bankroll, or take you from amateur to pro in one fell swoop. Winning an $11 MTT with 200 people is nice and nothing more. Winning the anniversary Sunday Storm at PokerStars covers all expenses for the year and gives you a bankroll to play a couple of limits higher.

4.6
PokerStars starting out holding online poker games back in 2001 and now the company is worth over 6 billion dollars. They sponsor a slew of tournaments like the European Poker Tour, UK and Ireland Poker Tour, plus a handful of others. Over the years, PokerStars has remained on top of the online poker industry. They’ve expanded to offer fantastic online casino games and sports betting.

The preponderance of good players in big fields is also higher. It seems that Andrew Brokos once said that a tournament with a thousand people cannot be strong, because there are simply not a thousand strong players.

Some top players are generous in estimating their ROI in big tournaments like the World Series Main Event as 200+%. In single-table tournaments, even the best of the best will not show a ROI above 10%. (This comparison is also a little lame, because the main structure is very slow and fluid, and in SNGs, the blinds usually rise quite quickly.)

I collected data from the winner of the SharkScope leaderboard, who played about the same number of SNGs for 6-18 people and for 27-90 people. His results in SNG 6-18:

And here are his tournaments with 27-90 participants:

As you can see, with an increase in the number of opponents, his ROI grows from 6.9% to 9.4%. At the same time, the percentage of hitting the money in small fields is slightly higher.

In an MTT with an average field of 802 players, his ROI is much higher at 20.6%:

Not a perfect comparison for many reasons, but at least we have a good sample of an obviously strong and profitable player. ROI grows as the field increases, but its graph behaves much more stable in small fields.

One of the reasons for the increase in ROI in big fields is that at their late stage, the role of experience sharply increases. The ability to play the complex bubble of the final table of a thousand-man tournament and adequately withstand the psychological pressure brings generous dividends. Weak players who find themselves at this stage often simply do not know what to do! It's enough to see how amateurs begin to play tighter on the bubble of the final table of the WSOP Main Event.

Bubble Factor

We argue that in large fields, ROI is higher, and in small fields, variance is lower. And how does this affect the strategy in terms of ICM?

General conclusion: The fewer participants, the tighter you should play. Each step on the prize ladder is more valuable, each bust out on the bubble is a disaster. Playing for first, willingness to take risks for a big stack that allows you to reach the final table – all this is more suitable for big fields. In those fields, you need to play looser.

Let's demonstrate this with numbers. In each example, we will have a 6-max table with an average stack of 40bb in a tournament where 25% of the field is left. Let's look at the dependence of the bubble factor on the size of the field.

SNG for 45 people, PokerStars. 11 players left:

The average bubble factor is 1.56, the Risk Premium is 10.9%. This means that everyone needs approximately 61% equity to go all-in against another player.

SNG for 90 people. 22 players left:

Under the same conditions, but with twice as many participants at the start of the tournament, the bubble factor drops to 1.38. The required equity for an all-in is 58%.

SNG for 180 people. 45 players left – again 25% of the field:

The bubble factor goes down even more – 1.22. You only need 55% equity to go all-in against an even stack.

And now the last one is a tournament for 1,666 people, in which 416 participants remain:

As you can see, the bubble factor here is the same as in the previous example, that is, there is a certain level below which it does not decrease in such spots.

The more players there are at the start of the tournament, the further away the generous payouts of the final table are from them, and the more you have to risk to get there. The conclusion is quite intuitive, isn't it?

The minimum prize in a small tournament is a larger percentage of the prize pool and therefore is valued more. In SNG-45 it is 3.5% of the prize pool, in SNG-90 it is 2.26%, in SNG-180 it is 0.65% and in MTT-1,666 it is a measly 0.2% of the prize pool.

Finally, when you enter short-stacked MTTs with a small field, you are much closer to the final table with its big payouts. You will need much fewer double-ups in all-ins for an overall victory than in a similar situation in a big field.

Conclusions

The size of the field in MTTs is a very important and possibly decisive factor when choosing a game.

Small fields attract with lower variance, it is easier to gain experience in them at all stages of the tournament, and they are much easier to play psychologically. They are harder to go broke and require a smaller bankroll to play.

Large fields are generally more profitable, but the results in them are much more volatile. Such tournaments require a larger bankroll and force players to take more risks in order to reach the final stage. In small fields, hitting the money and climbing the prize ladder is more important than in large ones, but you should not completely forget about caution in big fields either.

Strategically in small fields, you need to play tighter and push harder on the ICM. You should play noticeably looser in big ones.

Perhaps, ideally, you should connect tournaments of both types. Grinding small fields will help reduce variance and guarantee a reliable income, while big fields are worth playing for a shot, but regularly. That being said, it is important to remember that they require a slightly different strategy.