Plug in a decimal odds and your honest probability estimate — get EV %, the edge over the bookmaker's implied probability, and a recommended ¼ Kelly stake. EV is the primary indicator that a bet has long-run value.
Expected Value is the average net P/L per unit staked, weighted by your probability estimate. Positive means value exists — assuming your p is correct.
Where p is your probability the bet wins, odds are decimal (2.00 = even). The bookmaker's implied probability is simply 1 / odds. The gap between your p and implied — the edge in percentage points — is what the calculator highlights.
The Kelly fraction shown is the quarter Kelly we use across the entire system: 0.25 × (b × p − q) / b, where b = odds − 1 and q = 1 − p. Quarter Kelly cuts variance roughly in half versus full Kelly while keeping most of the growth.
A positive EV says the bet has value if your probability is right. The catch lives in three letters: i-f.
At p=0.55 over 100 bets, the 95% confidence interval on observed win rate spans roughly 45%–65%. You can be +EV and still lose for a year.
Bootstrap CI95 on ROI needs 200+ bets minimum to exclude zero — and that's at a clean +5% edge. Smaller edges need 500+. See methodology.
Your p is a model output. If the model is overfit to history, the EV is fantasy. The real question: does the closing line at Pinnacle agree with your p?
Expected Value is a number you compute before the bet, based on your probability — which may or may not be true. Closing Line Value is a number you compute after the line closes, comparing your price to the sharpest market consensus at game-start. CLV is the only honest feedback loop: it tells you whether the market eventually agreed with you. Positive average CLV across 200+ bets is the strongest single predictor of long-run profitability.
That's why Σ Value Sniper places a bet on EV ≥ 5%, but the system is judged on average CLV. Per ADR-008 lock parameters, real-money phase only begins after 200+ paper bets show consistent positive CLV. Read the full breakdown in the methodology page.
The engine computes EV against a sharp consensus fair line — the median of Pinnacle, Betfair Exchange, and Matchbook after stripping each book's margin. A signal fires when EV ≥ 5% on a soft book, and the bet is placed paper-only at quarter Kelly with a hard cap of 1.5% bankroll per bet.
EV is the entry filter. CLV is the verdict. Each settled bet logs its CLV against the closing Pinnacle line — and the running average CLV across the sample is the single number we judge the system on. Per ADR-008: EV ≥ 5% AND historical CLV positive — that's the lock.
Every bet in the public ledger logs both its pre-bet EV and its post-bet CLV. The relationship is the whole point — EV gets you in, CLV tells you if you were right.