Enter the price you can bet and your fair win probability. This tells you the expected value per dollar staked, as a percent and in dollars. A positive number is a +EV bet. The math runs live in your browser.
Every bet is a gamble with two outcomes. With probability p you win
and collect your profit, which on decimal odds dec is
(dec - 1) per dollar. With probability (1 - p) you lose
your dollar. Expected value is just the probability-weighted average of those two:
A positive result means the bet wins more, on average, than it risks: a +EV bet. Zero is breakeven. Negative means the price is worse than your estimate of the true odds.
To convert American odds to decimal: a positive price a becomes
a / 100 + 1 (so +150 is 2.50), and a negative price becomes
100 / |a| + 1 (so -110 is 1.9091). If you would rather enter fair
odds than a probability, the tool converts them for you with
p = 1 / fair_decimal. The breakeven probability shown is
1 / your_decimal: the win rate at which your price is exactly fair.
These are the exact cases the page self-tests on load. Probabilities are shown to 4 places, EV percent and dollars to 2.
| Your price | Fair p | Stake | EV% | EV $ |
|---|---|---|---|---|
| +100 (dec 2.00) | 0.5500 | $100 | +10.00% | +$10.00 |
| -110 (dec 1.9091) | 0.5500 | $50 | +5.00% | +$2.50 |
| +100 (dec 2.00) | 0.5455 (fair -120) | $100 | +9.09% | +$9.09 |
| -110 (dec 1.9091) | 0.4500 | $100 | -14.09% | -$14.09 |
| +110 (dec 2.10) | 0.5000 | $25 | +5.00% | +$1.25 |
| -150 (dec 1.6667) | 0.6000 | $100 | 0.00% | $0.00 |