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Expected Value Calculator
Put in the offered price, your stake and a fair win probability to see what the bet is worth on average.
Free, no account needed. Informational, not betting advice. 21+.
Results
- Expected value
- +10.00%
- EV on this stake
- +$10.00
- Fair odds
- +100
- Edge
- +4.55pts
- Offered price implies
- 45.45%
- Quarter-Kelly stake
- 2.08%of bankroll
The offered price beats the fair probability.
How it works
Expected value is what the bet is worth on average. Multiply the fair win probability by the decimal price and subtract 1. That is EV as a share of the stake; times the stake it is EV in dollars. Edge is the fair probability minus the probability the offered price implies. The quarter-Kelly stake is a conservative wager size for that edge, as a share of bankroll.
Worked example
+120 is decimal 2.20. At a fair 50%, EV is 0.5 × 2.20 − 1 = +10%, or +$10 on a $100 stake. The fair price is +100, the offered price implies 45.45%, and the edge is 4.55 points. Quarter Kelly is about 2.1% of bankroll.
When to use it
A check gives you the fair market price for a matched leg. Type that fair probability here with the price on your slip and you get the EV in dollars. If you only have a sharp two-way line, choose Devig a line and the tool removes the vig for you.
Questions
Where does the fair probability come from?
From a market with the vig removed, from your own model, or from a check. A sharp book’s two-way line is the usual source: type both sides and the tool devigs them with the multiplicative method.
Why is my EV negative?
The offered price implies a higher win rate than the fair probability. The difference is what the bet costs on average. That is normal at −110 against a fair 50%.
What does quarter Kelly mean?
A quarter of the full Kelly stake, the share of bankroll that maximises long-run growth if your probability is exactly right. Quarter Kelly assumes it is not, and cuts the swings a lot. The Kelly tool shows every fraction.
Is +10% EV a lot?
Yes. Most real edges on main markets are a point or two. A double-digit EV usually means the fair probability is optimistic, the line has moved, or the book has posted a mistake it will correct.
Is this betting advice?
No. The tool is arithmetic on the numbers you type. EdgeFast is informational price discovery, not a sportsbook, and you decide whether to bet. 21+ only.
Related tools
Now check a real price.
Screenshot a betslip and EdgeFast compares your price with the listed sportsbooks and a fair market price.
Informational, not betting advice. 21+.