Expected Value Betting Calculator
Calculate the expected monetary value of a bet — and across a series of identical bets — based on your true probability estimate versus the bookmaker's odds. Use it to identify which bets are genuinely profitable long-term.
About this calculator
Expected value (EV) measures the average profit or loss per bet if the same wager were repeated indefinitely. For a single bet with decimal odds the formula is: EV = (p × betAmount × (odds − 1)) − (q × betAmount), where p is your true win probability and q = 1 − p is the loss probability. Rearranging: EV = betAmount × (p × (odds − 1) − q). To project across a series, multiply single-bet EV by the number of bets: totalEV = singleEV × numberOfBets. A positive EV confirms a mathematical edge over the bookmaker. A negative EV means the bookmaker has the edge and you should expect to lose money over time. The formula also supports American odds by converting them: net profit per dollar = bookmakerOdds / 100 for positive lines.
How to use
You bet $50 on a match at decimal odds 2.20, and your true win probability is 55% (p = 0.55, q = 0.45). Net profit if win = $50 × (2.20 − 1) = $60. EV per bet = (0.55 × $60) − (0.45 × $50) = $33.00 − $22.50 = $10.50. Over 100 similar bets: total EV = $10.50 × 100 = $1,050. This means you can expect to profit $1,050 over 100 bets on average — though individual results will vary due to variance.
Frequently asked questions
What does a positive expected value in betting actually mean in practice?
A positive EV means that, on average, each bet returns more than it costs when repeated many times under identical conditions. It does not guarantee profit on any single bet or even over a short run — variance can produce losing streaks even with a strong edge. However, over hundreds or thousands of bets a positive EV strategy will tend to produce profits proportional to the edge and volume. Professional bettors focus on finding and betting positive EV opportunities consistently rather than predicting individual outcomes.
How do I estimate true win probability accurately for an expected value calculation?
Estimating true probability is the hardest and most important part of EV betting. Common approaches include building or using statistical models based on historical match data, tracking closing odds (which tend to be the most efficient market price), or comparing odds across multiple sharp bookmakers. Your true probability estimate should be independent of the bookmaker's implied probability, which already contains their margin. A useful sanity check is to remove the bookmaker's overround from their published odds and compare the resulting fair probability to your own estimate.
Why is expected value more important than win rate when evaluating a betting strategy?
Win rate alone does not capture the profitability of a strategy because it ignores the size of wins and losses. A strategy that wins 60% of bets at odds of 1.50 has a lower EV than one that wins 40% of bets at odds of 3.00, even though the win rate is higher. EV combines both probability and payout into a single metric that directly measures long-run profitability. Strategies with high win rates at short odds can still lose money, while low win-rate strategies at long odds can be highly profitable — EV is the only metric that correctly captures this distinction.