Free +EV Odds Calculator
Turn any betting odds into an implied probability, compare it to your own read on the game, and see the expected value — the edge, in dollars per $100. Free, instant, no signup.
This calculator is informational. An "edge" here is a comparison between a price and a probability you typed in. It is not a prediction, not a guarantee, and not gambling advice. 18+ only.
How to use this betting odds calculator
Three steps, and the math is the same one professional bettors run before every bet.
Enter the price
Type the odds your book is offering, in American or decimal format. The calculator reads them the way a book writes them.
Enter your read
Type how often you think that bet actually wins — your estimated probability out of 100. Injuries, form, rest, whatever your edge is.
Read the edge
The calculator converts the price to its implied probability, subtracts yours, and tells you the expected value on every $100 you risk.
+EV betting, explained
The one formula
Expected value = (win probability × decimal odds − 1) × stake. A +150 underdog is decimal 2.50. If it wins 45 times in 100, the EV is (0.45 × 2.50 − 1) = +0.125 — you keep 12.5% of everything you risk, on average. If it only wins 38 times in 100, the EV is −0.05: the same bet bleeds 5% of every stake. The price never changed; only the truth behind it did. That is why "who wins" is the wrong question and "how often" is the right one.
Why -110 is not a coin flip
The standard point-spread price, -110, implies 52.38% — not 50%. Those extra 2.38 points are the vig, the book's margin, and they are why long-term winners must clear 52.38% on every side of a coin-flip market. Decimal -110 is 1.909; implied probability is always 1 ÷ decimal odds.
Where a free calculator stops
A free EV calculator is only as good as the probability you type into it — the hard half of the problem. Betaware AI works on that half in the app: it pulls the live line from DraftKings and the Kalshi exchange, strips the vig into a consensus probability, researches injuries, form and head-to-head on the web, and puts a confidence score on its own number — then grades itself against final results.
Odds calculator FAQ
What is +EV in betting?
A bet is +EV (positive expected value) when your estimated chance of winning is higher than the probability the odds imply. Example: a team at +150 implies a 40% chance to win. If your read is 50%, the price pays more than the risk deserves — that gap is the edge.
How does this odds calculator work?
Decimal odds and implied probability are reciprocals: implied probability = 1 ÷ decimal odds. American +150 is decimal 2.50, so it implies 40%. Expected value = (your probability × decimal odds − 1) × your stake. This calculator does that arithmetic for you, per $100 staked.
What is implied probability?
The win probability baked into a price. -110 implies 52.38% — which is why a coin-flip bet at -110 loses money over time: you need better than 52.38% to break even. Books build their margin (the vig) on top of the true odds across both sides.
Is a +EV bet a guaranteed winner?
No. +EV means the price is in your favour over many repetitions, not that this one bet wins. Even a big edge loses most of the time in the short run. Bet sizes that assume the edge is real and repeatable; bankrolls that assume variance are brutal.
Is this betting calculator free?
Yes. This page is free to use with no account and no signup. Betaware AI also runs the same math inside the app — but against live lines pulled from DraftKings, Kalshi and other venues, plus the injury and form research behind the probability itself.
Betaware AI provides research and analysis for informational and entertainment purposes only. It is not gambling advice, and no outcome is ever guaranteed. Please gamble responsibly. See our responsible gambling page.
The hard half: where does the probability come from?
Betaware AI researches the matchup live and puts a graded confidence score on every answer.