The Concept That Changes Everything
Most bettors evaluate their picks with a single question: do you think this team is going to win? Professional bettors ask a different question: is the odds above or below the true probability?
That difference in approach is what separates those who win in the long run from those who lose.
What is Expected Value (EV)
Expected value (EV) is the average profit you would get per euro bet if you repeated that bet infinitely many times.
The formula is simple:
EV = (probability of winning × net gain) − (probability of losing × stake)
For example, imagine a fair coin. If it lands heads you win €2, if tails you lose €1. The EV is:
- EV = (0.5 × €2) − (0.5 × €1) = +€0.50 per bet
With a positive EV, although you can lose on a particular spin, you will make money in the long run.
Applied to Sports Betting
Suppose you estimate that team A has a 60% chance of winning a match. The bookmaker offers you odds of 2.00 (implying a 50% probability). Is there value?
Calculation:
- Your probability: 60% → 0.60
- Net gain if correct: €1 per €1 bet (odds 2.00)
- EV = (0.60 × 1) − (0.40 × 1) = +€0.20 per euro bet
There is positive value. In the long run, this bet is a winner even if you lose sometimes.
How to Identify Value Picks
Step 1: Estimate the True Probability
This is the hard part. To correctly estimate probability, you need:
- Team analysis (form, absences, motivation)
- Advanced statistics (xG, defense, pressing)
- Match context (second leg, relegation pressure...)
Step 2: Convert Odds to Implied Probability
The implied probability of odds is: 1 / odds
| Odds | Implied Probability |
|---|---|
| 1.50 | 66.7% |
| 2.00 | 50.0% |
| 3.00 | 33.3% |
| 5.00 | 20.0% |
Step 3: Compare
If your estimate is higher than the implied probability of the odds → there is positive value.
If your estimate is lower → there is negative value. Do not bet.
Remember that bookmakers include their margin (the "vig") in the odds. Odds of 1.90/1.90 in a 50/50 match already have margin built in. To win, you have to find odds where the bookmaker made a mistake.
The Role of Record Keeping in the Search for Value
You cannot know if you have a real edge without data. If you have 300 bets recorded with a positive ROI in a specific market, that is evidence you are finding value in that market.
With Oddfolio you can filter by market, bet type, or tag to know exactly in which areas you are profitable and in which you are not.
Conclusion
Betting with value does not guarantee winning every bet. It does guarantee making money in the long run if your probability estimates are correct. Work on your models, record your picks, and review your performance with real data.