Convert betting odds, see the break-even rate, and strip out the vig
Updated October 2026
American odds show the favorite with a minus sign (the amount you stake to win $100) and the underdog with a plus sign (what $100 wins). Decimal odds show the total return per $1, stake included; fractional odds show profit per unit staked. For −110: decimal = 1 + 100 ÷ 110 = 1.909; fractional = 0.909 = 10/11; implied probability = 1 ÷ 1.909 = 52.38%. A $100 stake wins $90.91 and returns $190.91. For +150: decimal 2.50, fractional 3/2, implied 40%.
Pick the format you have, type the odds as the sportsbook shows them, and add a stake to see profit and total return. Typing the opposite side’s American price adds the market overround, the hold and the no-vig fair probability.
| American | Decimal | Fractional | Implied probability | Profit on $100 |
|---|---|---|---|---|
| −300 | 1.333 | 1/3 | 75.00% | $33.33 |
| −200 | 1.500 | 1/2 | 66.67% | $50.00 |
| −150 | 1.667 | 2/3 | 60.00% | $66.67 |
| −110 | 1.909 | 10/11 | 52.38% | $90.91 |
| +100 | 2.000 | 1/1 | 50.00% | $100.00 |
| +150 | 2.500 | 3/2 | 40.00% | $150.00 |
| +200 | 3.000 | 2/1 | 33.33% | $200.00 |
| +300 | 4.000 | 3/1 | 25.00% | $300.00 |
Implied probability is the win rate at which a bet breaks even. Sportsbooks price both sides so the implied probabilities add up to more than 100%; the excess is their margin. With −110 on both sides, 52.38% + 52.38% = 104.76%, a hold of 1 − 1 ÷ 1.0476 = 4.55%; dividing each side by the total gives the fair 50%. With a favorite at −150 (60.00%) and an underdog at +130 (43.48%), the total is 103.48%, the hold 3.36%, and the no-vig chance for the favorite 57.98%, a fair price of −138.
A bet has positive expected value only if your honest estimate of the chance of winning is higher than the implied probability of the price. Because of the hold, a bettor picking sides at random loses money over time.
Treating implied probability as the true chance. It includes the book’s margin. Remove the vig before comparing it with your own estimate.
Mixing up decimal and fractional returns. Decimal 2.50 means $2.50 back per $1 including the stake; fractional 3/2 means $1.50 profit per $1. Both describe the same bet.
Dropping the sign. +200 and −200 are opposite bets: one pays $200 on $100, the other needs $200 to win $100.
Comparing prices across books by profit alone. Compare implied probabilities; the lower one is the better price for the same outcome.
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