Expected Value Calculator

Calculate whether a bet has positive or negative expected value

Formula:EV = (P × Win) - (Q × Stake)

Expected Value Calculator

Calculate EV, edge, and break-even probability

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+EV Bet

Positive expected value

Expected Value per $1
+12.50¢
+12.50% EV
EV on $100 stake: +$13
Odds
+150
2.50 decimal
Edge
+5.00%
Implied Prob
40.0%
Break-Even
40.0%

Probability Comparison

Implied (Book)40.0%
Your Estimate45.0%
This is a +EV bet. You estimate the true win probability (45.0%) is higher than what the odds imply (40.0%). Over many similar bets, you expect to profit 12.50% on average.

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Common EV scenarios

Bankroll Growth Simulator

Monte Carlo simulation with 1,000 iterations

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How EV is Calculated

Understanding the expected value formula

EV = (Win Prob × Profit) - (Loss Prob × Stake)

For a $100 bet at +150 odds with 45% estimated win probability:

Profit if win = $150
EV = (0.45 × $150) - (0.55 × $100)
EV = $67.50 - $55.00
EV = +$12.50 per bet

Quick Answer

Key concepts at a glance

Expected Value (EV) = (Win Probability × Profit) - (Loss Probability × Stake). A +EV bet has positive expected return. At +150 odds (40% implied), if you estimate 45% true probability, EV = (0.45 × $150) - (0.55 × $100) = +$12.50 per $100 wagered. Consistently finding +EV bets is the key to long-term profit.

Key Facts About Expected Value

Important concepts to understand

  • Expected Value measures the average profit/loss per bet over infinite iterations
  • +EV (positive expected value) means long-term profit is expected
  • Break-even percentage = 1 / decimal odds × 100
  • Edge = Your probability - Implied probability (positive edge = +EV)
  • A 5% edge at $100/bet over 1000 bets = $5,000 expected profit
  • Variance can make even +EV bettors lose in the short term
  • The best bettors typically find 2-5% edges on average

Frequently Asked Questions

Common questions about expected value

What is expected value in betting?

Expected value (EV) is the mathematical expectation of what you'll win or lose per bet over the long run. It accounts for both the probability of winning and the payout. A bet is +EV when your expected return is greater than your stake.

How do I estimate true probability?

True probability estimation requires research: team statistics, injury reports, weather, historical matchups, and market movement. Many use power ratings, models, or simply compare lines across multiple sportsbooks. If you can't estimate probability better than the market, you likely don't have an edge.

Why does EV matter more than win rate?

Win rate alone is misleading. A 60% win rate on -200 favorites loses money (break-even is 66.7%). A 35% win rate on +250 underdogs makes money (break-even is 28.6%). EV captures both probability AND payout, giving the true picture of profitability.

What is a good EV percentage?

Professional bettors typically find 2-5% edges. A 3% edge is considered good. Finding consistent 5%+ edges is excellent and rare. Remember that even small edges compound significantly over thousands of bets. A 2% edge at $100/bet over 5000 bets = $10,000 expected profit.

Can I lose money with +EV bets?

Yes, in the short term. Variance (luck) affects results over small sample sizes. A coin flip is 50/50, but you might flip heads 7 times in 10 flips. Over thousands of +EV bets, your results converge toward the expected value. This is why bankroll management is crucial.