How to use the calculator
To use the Expected Value Calculator, start by selecting your preferred odds format from the dropdown menu - Decimal, American, Fractional, Hong Kong, or Implied Probability. Enter the bookmaker's odds for the bet you're considering, then input either your estimated fair odds or win probability (the calculator will automatically convert between the two). Finally, enter your stake amount. The calculator will instantly display your expected value in both currency and percentage terms, along with a clear indicator of whether the bet is +EV, -EV, or break even. Use the pop-out option to keep the calculator open while you browse betting markets.
Understanding Expected Value in betting
Expected Value (EV) is the single most important concept in advantage betting. It represents the average amount you can expect to win or lose per bet if you were to place the same wager thousands of times. Professional bettors and sharp syndicates don't focus on individual wins or losses - they focus on finding and exploiting positive expected value.
A bet with positive expected value (+EV) means you have a mathematical edge over the bookmaker. Over time, consistently placing +EV bets is the only proven path to long-term profitability in sports betting.
The EV formula explained
The expected value formula calculates your average profit or loss by weighing potential outcomes by their probability:
EV = (Win Probability × Profit if Win) − (Loss Probability × Stake)
Or expressed as a percentage:
EV% = (Win Probability × Decimal Odds) − 1
For example, if you believe a team has a 50% chance of winning (fair odds of +100) but the bookmaker offers American odds of +120:
- Win Probability: 50% (0.50)
- Profit if Win: $100 × 1.20 = $120
- Loss Probability: 50% (0.50)
- Stake: $100
EV = (0.50 × $120) - (0.50 × $100) = $60 - $50 = +$10
This means on average, you'd profit $10 every time you place this bet. That's a +10% EV.
What makes a bet +EV?
A bet is +EV when the bookmaker's odds imply a lower probability than your estimated true probability. In simple terms: the bookmaker is offering you better odds than they should.
Scenario | Bookmaker Odds | Your Fair Odds | Result |
|---|---|---|---|
Bookmaker odds > Fair odds | +150 | +100 | +EV ✓ |
Bookmaker odds = Fair odds | +100 | +100 | Break Even |
Bookmaker odds < Fair odds | -125 | +100 | -EV ✗ |
The challenge isn't the maths - it's accurately estimating the true probability. This is where your edge as a bettor comes from.
How to estimate win probability
Estimating true probability is both an art and a science. Here are the most common approaches used by sharp bettors:
1. Pinnacle's closing line Pinnacle is widely regarded as the sharpest bookmaker in the world. Their closing odds (the final odds before an event starts) are considered the most accurate reflection of true probability. Many professionals use Pinnacle's implied probability as their baseline.
2. Consensus odds Compare odds across multiple sharp bookmakers and calculate the average implied probability. This "wisdom of the crowd" approach can help identify when a single bookmaker has mispriced a market.
3. Statistical models Build or use predictive models based on historical data, team statistics, player metrics, and other quantifiable factors. This approach requires significant expertise but can uncover edges invisible to the market.
4. Specialist knowledge Deep expertise in a specific league, sport, or market type can give you insights that oddsmakers miss - especially in lower-profile events with less liquidity.
A practical example
Let's say you're analyzing an NFL game where the Kansas City Chiefs are playing the Las Vegas Raiders.
The bookmaker offers: Chiefs to win at -152 American odds (implied probability: 60.3%)
Your analysis suggests: The Chiefs have a 68% chance of winning (fair odds: -213)
Using the EV Calculator with a $100 stake:
- Bookmaker odds: -152
- Your win probability: 68%
- Stake: $100
Results:
- Expected Value: +$12.74
- EV Percentage: +12.7%
- Verdict: +EV Bet ✓
This is a strong positive expected value bet. If your probability estimate is accurate, you'd expect to profit $12.74 on average for every $100 staked on similar spots.
Key takeaways
Concept | Description |
|---|---|
Expected Value (EV) | The average profit or loss per bet over the long run |
+EV Bet | A bet where you have a mathematical edge - the only type of bet professionals seek |
-EV Bet | A bet where the house has the edge - avoid these consistently |
Break Even | When bookmaker odds exactly match fair odds - no edge either way |
Win Probability | Your estimate of the true likelihood an outcome occurs |
Fair Odds | The odds that would represent zero edge for either side |
Expected value is the foundation of all successful betting strategies. While individual bets can win or lose regardless of their EV, consistently finding and betting +EV spots is the only mathematically proven way to profit from sports betting over time.
Our EV Calculator makes it simple to assess any betting opportunity in seconds - whether you're comparing odds across bookmakers, validating your model's outputs, or quickly sizing up a potential value bet.