📊 Bet analyzer
Calculate EV, edge, ROI, Kelly and build parlays in real time.
📊 Bet analyzer
Calculate expected value (EV), edge and Kelly in real time
⚠️ Educational tool. User estimates — not a guarantee or recommendation. 18+, gamble responsibly.
What it is
A bet analyzer calculates whether a given bet has positive expected value (EV) based on your estimated probability and the offered odds. It combines odds conversion, implied probability, edge, Kelly stake, and a parlay builder into one tool. The key output is the verdict—'Has value ✅' or 'No value ❌'—but that verdict is only as reliable as the probability you input.
How it works
The central formula is EV = (decimal odds × your probability) − 1. For example, odds of 2.50 with your probability of 45% yield EV = (2.50 × 0.45) − 1 = 1.125 − 1 = +0.125, or +12.5%. If your probability were 35%, EV = (2.50 × 0.35) − 1 = 0.875 − 1 = −0.125 (−12.5%). The implied probability from the odds is 1 ÷ 2.50 = 40%; your edge is the difference: 45% − 40% = +5%.
The calculator also suggests a Kelly stake: (edge × bankroll) ÷ (odds − 1). With a $1,000 bankroll, a 5% edge, and odds 2.50, Kelly stake = (0.05 × 1000) ÷ 1.50 = $33.33. The parlay builder multiplies odds and calculates combined implied probability and bookmaker margin.
How to use it
- Enter the decimal odds in the 'Odds (decimal)' field — the converter will show fractional and American equivalents.
- Input your estimated probability in 'Your probability (%)' — this is your assessment, not the implied probability from the odds.
- Optionally set a 'Stake (units)' and 'Bankroll (units)' to see Kelly stake and expected ROI in units.
- For parlays, use the 'Parlay builder' section: click 'Add leg' to enter each selection's odds, and read 'Combined odds' and 'Combined prob.'.
- Read the 'Calculated metrics' panel: check 'Edge', 'Expected value (EV)', and the 'Verdict' for a value flag.
- If using Kelly, review 'Suggested Kelly' and the corresponding 'Kelly stake' — it shows what fraction of your bankroll to risk.
How to read the result
- A positive EV (e.g., +12.5%) means that, if your probability is accurate, you expect to profit 12.5% of stake on average over many bets. A negative EV means expected loss.
- The 'Edge' compares your estimate to the implied probability; a positive edge does not guarantee the next bet wins, only a mathematical advantage over the long run.
- 'Suggested Kelly' is a fraction of your bankroll that maximizes long-term growth under the Kelly criterion. Using full Kelly can be aggressive; many bettors use a fraction (e.g., 1/4 Kelly).
- The 'Verdict' ('Has value ✅' or 'No value ❌') is a simple rule: value exists when your probability is higher than the implied probability. It is not a prediction.
When not to trust the result
- The EV and edge are entirely dependent on your probability estimate. If your model is poorly calibrated, the outputs will be misleading — garbage in, garbage out.
- Positive EV does not mean the next bet will win. Variance can produce long losing streaks even with a true edge; you need a large sample to realize expected value.
- Kelly stakes can be large and may exceed bet limits imposed by operators. Also, full Kelly is risky if your edge is overestimated — it can lead to large drawdowns.
- The parlay builder's combined probability assumes independence of legs, which is rarely true in correlated bets (e.g., same game props). It also compounds the house edge.
- Value signals can disappear quickly as odds move. The calculator gives a snapshot; by the time you act, the market may have shifted.
Frequently asked questions
- What does a positive EV mean in practice?
- A positive EV means that if you repeated the same bet many times, you would expect to profit on average. It does not guarantee you win this particular bet; it is a mathematical expectation, not a promise.
- How is the Kelly stake calculated?
- The Kelly stake is (edge × bankroll) ÷ (odds − 1). Edge is your probability minus the implied probability. It recommends the optimal fraction of bankroll to bet for maximum long-term growth, assuming accurate probability estimates.
- Should I always bet when the verdict says 'Has value'?
- No. The verdict is based solely on your input. A value verdict only means your probability exceeds the implied odds. You must trust your estimate and consider bankroll management, bet limits, and variance before betting.
- Why does the parlay builder show a higher combined margin?
- The bookmaker margin compounds across legs. If each leg has a 5% margin, a two-leg parlay has roughly a 10% margin on the combined price. That makes parlays harder to beat than single bets.