On this page 10
- Key points
- What an underdog is in esports betting
- How to read underdog odds
- When an underdog bet has value
- Why the series format changes the underdog's chances
- Spots where underdogs are often underpriced
- Upsets that show what is possible
- Bankroll rules for underdog bets
- Underdog betting terms
- Frequently asked questions
Key points
-
29%
Odds of 3.40 imply a 29.4% chance (1 / 3.40). You need a better reason than hope to rate the team higher.
-
40% → 35%
A team that wins 40% of maps wins about 35% of Bo3 series and 32% of Bo5 series. Longer series favour the stronger side.
-
+$1.90
Example: $10 at 3.40 on a team you rate at 35% returns $1.90 per bet on average. Rated at 25%, the same bet loses $1.50.
-
2018 & 2022
OG at The International 2018 and DRX at Worlds 2022 won titles as outsiders. Both are rare exceptions, not a pattern to copy.
What an underdog is in esports betting
The underdog is the side the bookmaker expects to lose, priced at the longer odds. In a CS2 match listed at 1.30 and 3.40, the team at 3.40 is the underdog. The label says nothing about the team's reputation: a famous organisation in poor form can be the outsider against a rising roster.
Esports produces more mispriced underdogs than most sports for a few structural reasons. Rosters change mid-season, patches shift the balance between play styles, many matches are best-of-one, and lower-tier teams get little coverage, so bookmakers often price them from thin data.
How to read underdog odds
Convert decimal odds to implied probability with 1 / odds. Add both sides together and the total above 100% is the bookmaker's margin. Remove the margin and you get the market's fair estimate.
Example: one CS2 match, example odds
The 3.40 underdog is a 28% shot after the margin is removed. Anything you rate above that is a potential value bet.
| Favourite | Underdog | |
|---|---|---|
| Decimal odds | 1.30 | 3.40 |
| Implied probability | 76.9% | 29.4% |
| Book total (margin) | 106.3% (6.3% margin) | |
| Fair probability (margin removed) | 72.3% | 27.7% |
Example odds for illustration, not a live price.
A $10 stake at 3.40 returns $34 (including the stake) if the underdog wins. That payout looks attractive, but the price already reflects the low chance. What matters is the gap between your estimate and the implied probability.
When an underdog bet has value
Expected value per bet is (your probability × odds) − 1, multiplied by the stake. With $10 at 3.40:
- You rate the team at 35%: 0.35 × 3.40 = 1.19, so +$1.90 per bet on average.
- You rate the team at 29.4%: 0.294 × 3.40 = 1.00, so you break even.
- You rate the team at 25%: 0.25 × 3.40 = 0.85, so −$1.50 per bet.
The fair odds for your estimate are 1 / probability. For 35% that is 2.86. If the best price you can find is shorter than your fair odds, skip the bet.
Why the series format changes the underdog's chances
Most esports matches are best-of-one, best-of-three or best-of-five. A weaker team needs to win one map in a Bo1, but two or three maps in longer series, and every extra map gives the stronger team another chance to show it. Assuming each map is independent:
Series win chance from a map win rate
A 40% map underdog drops from 40% to about 32% in a Bo5. The same team is a better underdog bet in a Bo1 than in a final.
| Map win rate | Bo1 | Bo3 | Bo5 |
|---|---|---|---|
| 30% | 30.0% | 21.6% | 16.3% |
| 40% | 40.0% | 35.2% | 31.7% |
| 45% | 45.0% | 42.5% | 40.7% |
Calculated: Bo3 = p²(3 − 2p), Bo5 = p³(10 − 15p + 6p²), independent maps.
Spots where underdogs are often underpriced
- Early in a new patch Teams that adapt quickly can beat stronger sides for a few weeks before the market catches up. See our guide to patch betting.
- Map veto edges In CS2 and Valorant, an underdog that gets its best map in the veto can be close to even on that map despite long match odds.
- Favourites with nothing to play for A favourite already through to playoffs may rotate strategies or rest key ideas. Read the format before you bet.
- Fresh roster changes on the favourite A new player or coach usually needs time. Prices often lean on the old roster's results.
- Regional leagues with thin coverage Bookmakers price lower-tier matches from less data. If you follow a region closely, this is where your knowledge is worth most.
Upsets that show what is possible
- The International 2018 (Dota 2): OG beat PSG.LGD 3–2 in the grand final.
- ELEAGUE Major Boston 2018 (CS:GO): Cloud9 beat FaZe Clan 2–1 in the final, the first Major won by a North American team.
- Worlds 2022 (League of Legends): DRX started in the play-in stage as the LCK's fourth seed and beat T1 3–2 in the final.
Bankroll rules for underdog bets
Even a well-chosen 3.40 underdog loses about seven times in ten. Losing runs are normal: at a 30% hit rate the chance of five losses in a row is about 17% (0.75). Keep each stake to 1–2% of your betting bankroll, never raise stakes to win back losses, and track every bet so you can check whether your estimates beat the odds over time.
Glossary
Underdog betting terms
- Underdog
- The side priced at the longer odds, expected to lose. So what: Long odds are only good when they are longer than the real chance justifies.
- Implied probability
- The chance the odds suggest: 1 divided by the decimal odds. So what: Compare it with your own estimate before every bet.
- Value bet
- A bet where your estimated probability times the odds is above 1. So what: Value only shows up over many bets, not in one result.
- Map handicap
- A bet that gives one team a head start in maps, for example +1.5 in a Bo3. So what: It lets you back an underdog to win at least one map at shorter odds.
Frequently asked questions
What is an underdog in esports betting?
The team or player the bookmaker expects to lose, shown at the longer odds. In a match priced 1.30 and 3.40, the side at 3.40 is the underdog.
Why do underdog bets pay more?
Because the bookmaker rates the chance of winning lower. Odds of 3.40 imply about 29%, so a winning $10 bet returns $34 to cover all the times it loses.
Is betting on underdogs profitable?
Only when your probability estimate is better than the bookmaker's. Backing every underdog loses money over time because each price includes a margin.
Which format is best for underdog bets?
Best-of-one matches. A team that wins 40% of maps has a 40% chance in a Bo1 but only about 35% in a Bo3 and 32% in a Bo5.
What is a +1.5 map handicap?
A bet that the underdog wins at least one map in a Bo3. It pays less than the match winner but wins more often.
How much should I stake on an underdog?
Keep it to 1–2% of your betting bankroll. At a 30% hit rate, five losses in a row happen about 17% of the time.
