It sounds like a simple question. Favorites win more often, so bet favorites. Underdogs pay more, so bet underdogs when you want a big return.
Neither of those approaches is correct, and understanding why is one of the most important things you can learn as a UFC bettor.
What the data actually says
Over the last decade of UFC fights, favorites win approximately 65% of the time. Underdogs win around 35% of the time. That sounds like a clear case for betting favorites.
But winning percentage alone does not determine whether a bet is profitable. What matters is whether the odds you are being offered accurately reflect those percentages.
Here is the problem with favorites: bookmakers know they win 65% of the time too. The odds on favorites already price in that advantage. When you bet a fighter at -300, you are getting implied odds of 75% on a fighter who might only win 65% of the time. You are paying more than the probability justifies.
Underdogs present the opposite dynamic. Because public money consistently flows toward well-known fighters and favorites, bookmakers adjust their lines to account for that imbalance. The result is that underdogs are frequently priced at lower implied probabilities than their actual win rate justifies.
Research across historical UFC data shows that underdogs in the slight to moderate range, roughly +120 to +200, have consistently outperformed their implied win probability. Blindly betting every underdog in that range over a large sample has historically produced a small but positive return on investment.
Blindly betting every heavy favorite over the same period has produced a negative return.
Why favorites are often overpriced
Public betting behavior creates inefficiencies in UFC markets that favor sharp bettors over casual ones.
When a well-known fighter is heavily promoted before a card, casual bettors bet them regardless of the odds. This pushes the favorite's line shorter and shorter as fight night approaches. By the time you place your bet, the market has absorbed a significant amount of public money and the value has been squeezed out.
The fighter is just as likely to win as they were before the public money arrived. But your potential return has shrunk considerably.
Conversely, when a lesser-known fighter is matched against a bigger name, public money largely ignores them. Their odds drift longer as more money flows to their opponent. In some cases, the market ends up offering better odds on the underdog than their actual probability of winning justifies.
That is not always the case. But it happens often enough that underdogs represent better value on average across the UFC moneyline market.
The range that matters most
Not all underdogs are equal, and the data reflects this clearly.
Extreme underdogs, those priced at +500 or higher, win only a small fraction of the time. The occasional massive upset can skew returns on a small sample, but over a large number of fights, betting big underdogs consistently produces poor results. The odds may look attractive, but the implied win probability is still too generous compared to reality.
The most interesting range historically is the slight underdog, roughly +120 to +200. These are fighters the market considers less likely to win, but only marginally. In this range, the gap between market implied probability and actual win rate has been large enough to produce positive expected value over time.
This makes intuitive sense. When a fight is close, public bias toward the more recognizable fighter tends to be strongest relative to the actual skill gap between the two competitors.
Heavy favorites carry their own risk
Beyond the value problem, heavy favorites carry a risk that their odds do not adequately compensate for.
In MMA, a single punch can end a fight at any moment. A submission attempt can come from a position that looked controlled one second earlier. A cut can stop a fight. These low-probability events exist in every fight, and when you bet a fighter at -400 or -500, you are getting virtually no compensation for that uncertainty.
A fighter at -500 loses one time in six on average. When they do lose, you lose your full stake. The five wins before that each return roughly two cents on the dollar. The math of heavy favorites is brutal over time.
Several times per year, a dominant champion or overwhelming favorite loses in a way that shocks the entire sport. Those upsets look improbable but they are priced as if they are nearly impossible. That is the distinction that matters.
What this means in practice
None of this means you should blindly bet every underdog on every card. The data shows that underdogs as a category represent better value on average, but average does not win you money on individual fights. You still need to do the analysis to identify which specific underdog represents genuine value in a specific matchup.
The right approach is to let the data set your starting assumptions and then do the work to identify exceptions. Start with the knowledge that heavy favorites are often overpriced and underdogs in the slight range are often underpriced. Then evaluate the specific matchup to determine whether that general trend applies.
Sometimes a heavy favorite is correctly priced. Their opponent genuinely has very little chance. Betting the underdog in that situation just because they are an underdog is not value betting, it is wishful thinking.
Sometimes a significant underdog has a stylistic advantage that the market has not fully accounted for. That is where genuine value can be found.
The goal is always the same: find situations where the market's implied probability is meaningfully different from what the analysis suggests. Whether that leads you to a favorite or an underdog on a given fight is secondary to the question of whether the price is right.
The question to ask before every bet
Before placing any UFC bet, favorite or underdog, ask yourself one question.
Does my estimated probability of this fighter winning justify the odds being offered?
If you think a fighter has a 70% chance of winning and the market is offering implied odds of 60%, bet them regardless of whether they are the favorite or underdog. If you think a fighter has a 60% chance of winning and the market is offering implied odds of 70%, pass regardless of how confident you feel about the outcome.
That framework removes the underdog versus favorite question entirely and replaces it with the only question that actually matters: is there value in this bet at this price.
— Eddie, Data Scientist · Fight Metrics Pro
18+ only. Sports betting involves risk. You may lose money. Past performance does not guarantee future results.
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