Implied probability turns odds into a percentage. The formula is 1 ÷ decimal odds. -110 (1.91) implies 52.4%, +150 (2.50) implies 40%.
It's also your break even win rate at those odds: win more often than the implied probability and the bet makes money over time.
Add up the implied probability of every outcome in a market and you'll get more than 100%. The extra is the vig. Remove it to find the fair odds.
How it works
Implied probability is the bridge between odds and your own opinion. Odds tell you what the sportsbook charges. Implied probability tells you what chance of winning that price assumes.
To use it, compare the implied probability with your own estimate. If a team is +150 (40% implied) and you think they win 45% of the time, the price may be good. If you think they win 35% of the time, it isn't.
For American odds, you can work it out directly:
- Negative odds: odds ÷ (odds + 100). -150 is 150 ÷ 250 = 60%.
- Positive odds: 100 ÷ (odds + 100). +150 is 100 ÷ 250 = 40%.
Remember that implied probability includes the vig, so it slightly overstates every outcome's chance. For a fairer estimate, strip the margin out with the no-vig calculator to get the fair odds. And remember it's the sportsbook's view, not the truth. The whole idea of finding value is disagreeing with it correctly.
Examples
- Example 1
Both sides at -110 imply 52.4% each, 104.8% in total. The 4.8% extra is the sportsbook's margin.
- Example 2
-250 implies a 71.43% chance (250 ÷ 350).
- Example 3
+300 implies a 25% chance (100 ÷ 400), so it should win about one time in four.
- Example 4
Decimal odds of 2.20 imply 45.45%. If you rate the outcome at 50%, the bet has positive expected value.
Read more: How to read betting odds
Common questions
How do I convert odds to a percentage?
Divide 1 by the decimal odds. For American odds, use 100 ÷ (odds + 100) for plus odds and odds ÷ (odds + 100) for minus odds, ignoring the minus sign.
What is the implied probability of -200?
66.67%. You risk $200 to win $100, so you need to win two out of every three bets just to break even.
Why do implied probabilities add up to more than 100%?
Because the sportsbook builds its margin into every price. The amount over 100% is the overround.