Positive EV Calculator
See whether a price carries positive expected value — compare your odds to a fair line and get the EV%, fair odds, edge, and a suggested stake.
We remove the vig from the two sharp prices to get the fair probability. e.g. +150 or -110
Omenizer computes the fair line and EV on every market automatically — and shows how similar +EV bets actually performed.
See live +EV bets →How it works
fair_prob = no-vig probability (from sharp odds) or your input EV% = fair_prob × your_decimal_odds − 1 edge (pts) = fair_prob − (1 / your_decimal_odds) ¼ Kelly = 0.25 × (b·p − q) / b (b = dec−1, p = fair_prob, q = 1−p)
Worked example
Your side is available at +120 (decimal 2.20). The sharp market prices it +100 / −120. Devig: 50.0% + 54.5% = 104.5% total, so the fair probability of your side is 50.0 ÷ 104.5 = 47.8% (fair odds ≈ +109). At +120 your EV = 47.8% × 2.20 − 1 = +5.2%, an edge of about +2.3 points over the fair line — a clear positive-EV bet.
EV by the price you get (fair probability 50%)
When the fair price is +100 (a true 50% shot), every extra point of price is pure edge — and every point worse is negative EV.
| Your price | Decimal | EV |
|---|---|---|
| +130 | 2.30 | +15.0% |
| +120 | 2.20 | +10.0% |
| +110 | 2.10 | +5.0% |
| +100 | 2.00 | 0.0% |
| −110 | 1.91 | −4.5% |
| −120 | 1.83 | −8.3% |
| −140 | 1.71 | −14.3% |
FAQ
- What is positive EV?
- A bet has positive expected value when the price you get pays more than the true probability of the outcome warrants. Over many such bets, positive EV is what makes betting profitable.
- How do you find the fair probability?
- From a sharp, low-margin market: take both sides’ odds, remove the vig, and the no-vig probability is your fair estimate. Or enter a fair probability directly if you already have one.
- What does the EV% mean?
- It’s your expected return per unit staked. +4% EV means that, on average, you’d expect to win 4 cents per $1 over a large sample at that price and true probability.
- What is the Kelly stake?
- Kelly is the mathematically optimal bet size to maximize long-run growth given your edge. Most bettors use a fraction (¼ Kelly) to reduce variance — that’s what we suggest.
- What counts as a good EV%?
- Anything positive beats the market long-term, but real, sustainable edges are usually small — often +1% to +5%. Be suspicious of huge EV numbers; they usually mean a stale line, a limit-you bet, or a bad fair-probability estimate.
- Why is my fair probability so important?
- EV is only as good as the probability you feed it. Use the no-vig price from the sharpest market you can find. A fair probability that’s off by a couple of points can flip a bet from +EV to −EV.
- Positive EV vs. arbitrage — what’s the difference?
- Arbitrage locks a guaranteed profit by betting both sides across books; +EV bets one side at a price better than fair and profits on average over time. +EV has higher variance but far more opportunities and higher long-run returns.
- Does +EV betting get you limited?
- It can — books restrict consistent winners. Bet sizing, market selection, and spreading action across books all help you last longer.
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Built by the team behind Omenizer’s real-time fair-odds engine — the same devigging and closing-line-value math that powers our live value-bet feed. Last updated July 2026.
Educational tool only. Not betting advice or a guarantee of profit. EV assumes your fair probability is accurate — the sharper your source, the better the estimate.