Expected Value (EV) Calculator
Calculate expected value to find profitable bets. Positive EV = long-term profit.
What is Expected Value?
Expected value (EV) is the average amount you expect to win or lose per bet if you made the same bet thousands of times. It's the single most important concept in profitable betting.
- +EV (Positive EV) — The bet is profitable long-term. You have an edge.
- -EV (Negative EV) — The bet loses money long-term. The house has the edge.
- 0 EV — Break-even. No edge either way.
The key insight: you need to estimate the true probability better than the market. If you think a team has a 50% chance of winning, but the odds imply only 45%, you have edge.
Example Calculation
Example: Lakers at +150, you estimate 45% win probability
The odds +150 imply a 40% probability (100 / 250 = 0.40).
You estimate 45% — that's 5% higher than the market. You have edge.
Profit if win: $150
EV = (0.45 × $150) − (0.55 × $100)
EV = $67.50 − $55.00
EV = +$12.50 per bet (12.5% of stake)
Example: Patriots at -110, you estimate 50% win probability
The odds -110 imply 52.4% probability. You only think it's 50%.
The market thinks they're more likely to win than you do. No edge.
EV = (0.50 × $100) − (0.50 × $110)
EV = $50.00 − $55.00
EV = −$5.00 per bet (−4.5% of stake)
Frequently Asked Questions
What's a good EV percentage to target?
Professional bettors often target +2% to +5% EV. Even small edges compound significantly over hundreds of bets. A +3% edge on 1,000 bets at $100 each = $3,000 expected profit.
How do I estimate probability accurately?
This is the hard part. Use historical data, statistical models, situational factors (injuries, rest, etc.), and compare across multiple sportsbooks. The closing line is often the most accurate — if you consistently beat the closing line, you likely have edge.
Why can I still lose money on +EV bets?
Variance. A +EV bet can still lose — it's only profitable in expectation over many bets. You need proper bankroll management (see Kelly Criterion) to survive the inevitable losing streaks.
How does this relate to the bookmaker's vig?
The vig (juice) is baked into the odds. Standard -110/-110 markets have ~4.5% vig. To be +EV, your edge must overcome the vig. That's why finding soft lines and shopping across books matters.