Enter your estimated probability and the bookmaker's odds to instantly calculate expected value and determine if a bet has a positive edge.
A value bet occurs when the probability of an outcome is greater than what the bookmaker's odds imply. If you estimate a team has a 55% chance of winning and the odds imply only 45%, you have a +10% edge — a value bet.
EV = (Win Probability × Profit) − (Loss Probability × Stake)
For decimal odds of 2.20 with a 55% win estimate: EV = (0.55 × 1.20) − (0.45 × 1) = 0.66 − 0.45 = +0.21 per unit
Short-term results are dominated by luck. Over hundreds of bets, positive EV reliably converts to positive ROI. Focusing on edge (EV) rather than outcomes is the foundation of professional betting.
Probability estimation is the hardest part of value betting. Approaches include: building statistical models, comparing line movements across bookmakers, using a sharp bookmaker's opening line as a baseline, or applying domain expertise. No method is perfect — track your estimates vs actual results over time to calibrate your model.
Any positive EV is theoretically good. Practically, value bettors look for edges of 3%+ per bet to overcome variance and account for model uncertainty. An EV of 5-10% per bet is excellent and quite rare to find consistently.
Yes — combine this calculator with our Kelly Criterion calculator. Once you know your edge %, Kelly tells you the optimal fraction of your bankroll to stake. Most value bettors use half-Kelly (50% of the full Kelly stake) to reduce variance.
In 2026, don’t judge a “value” bet from one soft-book price alone. Before staking, compare your edge against the current sharp/closing market on an odds screen or exchange. If your calculator says +6% EV at 2.20, but the sharp consensus is already 2.35, your “edge” is probably model error or stale data. As a practical rule, only trust calculated value when your fair odds beat both the offered price and the broader market after commission, especially on player props and same-game markets.