Free calculator
Expected value calculator
Last reviewed August 2026
The calculator
Expected value is an average over many identical bets, not a forecast for this one. At 2.30 this bet loses 53.62% of the time however positive the edge is. Size it with the Kelly calculator.
The formula
Expected value is what a bet returns on average if you could repeat it forever. For a decimal price it is one multiplication:
edge = p × offered − 1
// break-even price
fair odds = 1 / p
// worked: fair 2.156 (p = 46.38%), offered 2.30
0.4638 × 2.30 − 1 = +6.67%
Equivalently: the bet is +EV whenever the offered odds exceed 1 / p. Here break-even is 2.156 and you are being offered 2.30, so every 100 staked returns an expected 106.67.
Where the probability comes from
This is the part that decides whether the number above means anything. The formula is trivial; the estimate of p is the entire problem, and a confident edge computed from a bad probability is worse than no edge at all because it tells you to bet.
Nobody knows a true probability. What is available is the opinion of a bookmaker with a strong incentive to be right. Pinnacleoperates on thin margins, accepts very large stakes, and does not restrict winning customers — a book doing all three cannot afford an inaccurate line, because sharp money will find it. Strip the margin out of Pinnacle's price with the no-vig calculator and you have the best cheap estimate of p there is.
Then compare it against a different, softer book. Comparing a book to itself is circular: de-vig Bet365 and compare to Bet365 and the edge is zero by construction. The value comes from the disagreement between a sharp line and a soft one.
What +EV does not mean
A positive edge is not a good bet, it is a good price
At 2.30 the bet loses roughly 54% of the time. A +6.67% edge means that across hundreds of such bets you expect to end ahead — it makes no claim at all about this one, and a run of ten losses in a row is unremarkable.
Three things the number does not survive contact with:
- Sample size. Edges of a few percent need several hundred bets before results distinguish them from noise. Judging a method on thirty bets is judging variance.
- Stale prices.If the soft book has simply not updated, the "edge" is a measurement of their laziness and will be gone or corrected before it settles. This is why large apparent edges are more suspicious than small ones.
- Account limits. Soft bookmakers restrict customers who consistently take the best price. The edge is real; the ability to keep betting into it is finite.
The honest way to check whether your edges were real is closing line value — did the price you took beat the price the market settled on? That answers in dozens of bets what profit takes hundreds to answer.
Frequently asked questions
How do you calculate expected value on a bet?
Expected value per unit staked is the true probability multiplied by the decimal odds, minus 1. If an outcome's true chance is 46.38% and a bookmaker offers 2.30, the edge is 0.4638 × 2.30 − 1 = +6.67%. On a 100 stake that is an expected +6.67, averaged over many identical bets.
What does +EV mean in betting?
Positive expected value: the price on offer pays more than the outcome's true probability justifies, so repeating that bet indefinitely gains money on average. It says nothing about whether this particular bet wins — a +6.67% bet at odds of 2.30 still loses about 54% of the time.
Where do I get the true probability from?
You estimate it, and the standard estimate is a sharp bookmaker's price with the margin removed. Pinnacle is the usual reference because its low margins, high limits and willingness to accept winning customers force its line to be accurate. Use the no-vig calculator to convert its price into a fair probability first.
How much edge is worth betting?
Genuine value at a soft book against a sharp line typically shows up between 1% and 6%. Above roughly 10% the likeliest explanations are a stale price, a market the soft book has stopped maintaining, or a fixture matched to the wrong event — not a gift. Very small edges are real but get eaten by the time it takes to place the bet.
Is expected value the same as closing line value?
No, and the difference matters. Expected value is your estimate at the moment you bet. Closing line value compares the price you got against the final price before kickoff, which is the market's best estimate — it is evidence after the fact that your edge was real. You can have positive EV by your own numbers and negative CLV, which usually means your estimate was wrong.
Does a positive expected value guarantee profit?
No. It guarantees profit only in the limit of infinitely many bets, and the variance around that is large. Hundreds of bets are needed before results say much, and losing months are entirely normal at the edges available in practice.
For research, not betting advice. Positive expected value is an edge across many bets, never a prediction about one. Bet only what you can afford to lose. 18+.