Odds Format
Stake ($)
Odds
Win Probability (%)
Results
Enter stake, odds and win probability to see results.
What Is It?
Expected Value is the most important concept in profitable betting. It tells you how much you can expect to win or lose per bet on average over a large number of identical bets. A positive EV (+EV) means the bet is profitable long-term; a negative EV (-EV) means you’ll lose money over time.
The EV Calculator takes the odds offered, your estimated probability of winning, and the stake, then computes the expected value, edge percentage, and implied probability of the odds. This allows you to compare your estimated probability against the bookmaker’s implied probability.
Professional bettors use EV as the primary filter for every wager. If a bet isn’t +EV, they don’t place it ā regardless of how “likely” the outcome seems.
How to Use
Formulas & Data Sources
Where: p = your estimated probability of winning (as decimal), Odds = decimal odds, Profit if win = Stake x (Odds – 1), Loss if lose = Stake.
All data is user-supplied. The “true probability” is your own estimate ā sourced from your research, models, or statistical analysis.
Real-World Scenarios
A bookmaker offers 2.20 on Team A to win. The implied probability is 1/2.20 = 45.5%. Your model says Team A has a 52% chance. EV per $100 = (0.52 x $120) – (0.48 x $100) = $62.40 – $48.00 = +$14.40.
Odds of 1.50 on a heavy favorite imply a 66.7% win probability. If the true probability is only 60%, EV per $100 = (0.60 x $50) – (0.40 x $100) = $30 – $40 = -$10.
Bookmaker A offers 1.85 and Bookmaker B offers 1.95 on the same outcome. With a 55% true probability: EV at 1.85 = +$1.75. EV at 1.95 = +$7.25.
Frequently Asked Questions
QHow do I know the 'true' probability?
You don’t know it with certainty. Use statistical models, historical data, expert analysis, or tools like the Poisson Calculator to estimate it. The better your estimate, the more useful the EV calculation.
QCan a +EV bet still lose?
Absolutely. EV is a long-term average. A +EV bet can lose today, tomorrow, and the day after. But over hundreds or thousands of bets, +EV bettors come out ahead.
QWhat's a good edge percentage?
In sports betting, edges of 2-5% are common for skilled bettors. Edges above 5% are excellent but rare. Any positive edge, consistently applied, generates profit over time.
QShould I always bet the maximum on +EV bets?
No. Stake sizing matters. Use the Kelly Criterion Calculator to determine the optimal stake based on your edge size and bankroll.
