Understanding Positive EV Betting
Learn how to identify profitable betting opportunities using Expected Value and Kelly Criterion
What is Expected Value (EV)?
Expected Value is the average amount you can expect to win or lose per bet in the long run
In sports betting, positive EV (+EV) means a bet has a mathematical edge in your favor. Over many bets, you'll profit. Negative EV means you'll lose money over time.
Method 1: OddsQuanta (Devig All Books)
We use all available sportsbooks to establish true market probabilities through devigging (removing bookmaker margins).
- 1. Collect odds from all major sportsbooks for both sides of a market
- 2. Remove the vig (overround) to get no-vig probabilities that sum to 100%
- 3. Compare these true probabilities to each sportsbook's odds to find +EV opportunities
Example: Finding +EV with OddsQuanta
FanDuel has Team A at -120, Team B at +100
DraftKings has Team A at -110, Team B at -110
After devigging all odds, true probability for Team A is 52%
BetMGM has Team A at +110 (2.10 decimal, 47.6% implied)
• True win probability (devigged): 52%
• BetMGM decimal odds: 2.10
• Expected return: 0.52 × 2.10 = 1.092
EV% = (1.092 - 1) × 100 = +9.2%
On a $100 bet, you expect to profit $9.20 on average
✓ Why OddsQuanta Method is Recommended
- • Uses the collective wisdom of all sportsbooks, not just one
- • More accurate in markets where Pinnacle doesn't offer odds (player props, futures)
- • Adapts to market movements across all books in real-time
- • Reduces dependency on a single sportsbook's lines
Method 2: Pinnacle (Sharpest Book)
We use Pinnacle as the sharp book to establish true market probabilities. Pinnacle is widely considered the sharpest sportsbook with the lowest margins and highest limits.
- 1. Take Pinnacle's odds and remove the small vig (overround) to get no-vig probabilities
- 2. These no-vig probabilities represent the true market consensus
- 3. Compare these true probabilities to other sportsbooks' odds to find +EV opportunities
Example: Finding +EV with Pinnacle
Pinnacle has Team A at -150 (1.67 decimal, 60% implied)
After removing vig, Pinnacle's no-vig probability for Team A is 58%
DraftKings has Team A at +120 (2.20 decimal, 45.5% implied)
We use Pinnacle's 58% true probability with DraftKings' 2.20 odds:
• True win probability (from Pinnacle): 58%
• DraftKings decimal odds: 2.20
• Expected return: 0.58 × 2.20 = 1.276
EV% = (1.276 - 1) × 100 = +27.6%
On a $100 bet, you expect to profit $27.60 on average
💡 Why Pinnacle Method Works
- • Pinnacle has the lowest margins (typically 2-3% vs 5-10% at other books)
- • Accepts sharp bettors and high limits, so lines are very efficient
- • Often sets the market - other books follow Pinnacle's lead
- • Best for main markets (moneyline, spreads, totals) where they always have odds
⚠️ When to Use Each Method
Use OddsQuanta Method for:
- • Player props and derivatives
- • Markets where Pinnacle doesn't offer odds
- • Maximum accuracy across all markets
Use Pinnacle Method for:
- • Main markets (ML, spreads, totals)
- • When you trust Pinnacle as the sharpest
- • Simpler, more conservative estimates
Kelly Criterion
A formula to calculate optimal bet size based on your edge
The Kelly Criterion tells you how much of your bankroll to bet on a +EV opportunity to maximize long-term growth while minimizing risk of ruin.
Kelly Formula
Or simplified: Kelly% = Edge / (Decimal Odds - 1)
Example: Calculating Kelly%
Using the same bet from above:
• True win probability: 35% (0.35)
• True loss probability: 65% (0.65)
• Decimal odds: 3.50
Kelly% = (0.35 × (3.50 - 1) - 0.65) / (3.50 - 1)
Kelly% = (0.35 × 2.50 - 0.65) / 2.50
Kelly% = (0.875 - 0.65) / 2.50
Kelly% = 0.225 / 2.50
Kelly% = 0.09 or 9% of bankroll
✓ With a $1,000 bankroll, Kelly suggests betting $90 on this opportunity
Fractional Kelly (Recommended)
Most professional bettors use fractional Kelly to reduce variance
Full Kelly can be aggressive and lead to large bankroll swings. Most pros use quarter Kelly (0.25×) or half Kelly (0.5×) for more conservative bet sizing.
Example with Kelly Fractions
If full Kelly suggests 9% of bankroll ($90 on $1,000):
• Half Kelly (0.5): 4.5% = $45
• Quarter Kelly (0.25): 2.25% = $22.50
✓ Benefits of Fractional Kelly
- • Reduces variance significantly
- • Protects against estimation errors
- • More sustainable long-term
- • Easier psychologically
⚠ Full Kelly Risks
- • Large bankroll swings
- • Sensitive to probability errors
- • Can be emotionally difficult
- • Higher risk of ruin if wrong
Important Considerations
- •Line movement: Odds change quickly. A +EV bet now might not be +EV in 5 minutes
- •Limits: Books may limit or ban winning players. Start small to fly under the radar
- •Bankroll management: Never bet more than you can afford to lose. Variance is real
- •Volume matters: EV betting is a volume game. You need many bets for the math to work