How the value bet calculator works
EV = stake × (probability × odds − 1)
It multiplies the probability by the total return and subtracts the stake. Positive means the odds pay more than the chance deserves (+EV); negative means you are paying too much. Any odds format works: decimal (2.10), American (+110) or fractional (11/10).
Example
Odds 2.10, fair odds 1.97 (a win probability of 50.8%), stake 100. If it wins you profit 110; if it loses you lose 100. EV = 0.508 × 110 − 0.492 × 100 = +6.60, which is +6.6% of the stake. The break-even probability at 2.10 is 47.6%, so the edge is about +3.2 percentage points.
Where do I get the probability?
That's the hard part, and the result is only as good as the input. The best practical source is the price of the sharpest market with its margin removed: use the no-vig calculator, then paste its fair odds here (choose 'I know the fair odds'). Read how to find value bets.
How to read the results
- EV: the average result of this bet if you could repeat it forever, in money.
- EV %: the same as a percentage of your stake (also called the edge or ROI per bet).
- Break-even probability: 1 ÷ odds. You need to win more often than this to profit.
- Edge (points): your probability minus the break-even probability.
- Minimum odds for value: 1 ÷ probability, the same as the fair odds. Any price above it is +EV.
One bet's EV says nothing about how this one will end. It describes the long run: see expected value betting for how many bets it takes to show. To size the stake, use the Kelly calculator.