How betting odds work
What -110 and +150 actually mean, how to turn any price into a percentage, and where the sportsbook takes its cut.
That win chance has the sportsbook's cut baked in, so the real chance is a little lower — compare it with your own estimate to judge the price.
Favorites are negative (-150), underdogs are positive (+130)
The three odds formats
- American — +150 / -110
- Negative is the favorite — the number is what you risk to win $100. Positive is the underdog — the number is what you win on $100 risked.
- Decimal — 2.50
- One multiplier of your stake, including the stake itself: $100 at 2.10 returns $210, so $110 profit. Standard outside the US.
- Fractional — 3/2
- Profit against stake, mostly British: 5/2 means $5 profit on $2 risked. Add the fraction to 1 for decimal — 5/2 → 3.50, which US books show as +250.
Common prices
| Odds | Risk → win | How often it must win |
|---|---|---|
| -110 | $110 → $100 | 52.4% |
| -150 | $150 → $100 | 60.0% |
| +150 | $100 → $150 | 40.0% |
| -300 | $300 → $100 | 75.0% |
| +500 | $100 → $500 | 16.7% |
Every price is also a win chance (implied probability)
The percentage in that table is how often the bet has to win for you to come out level. It is the number to argue with — if you think a +150 underdog wins 45% of the time when its price implies 40%, the price is paying more than the outcome is worth. That gap is what a value bet is.
Where the sportsbook takes its cut (the vig)
Add up how often each side of a bet has to win. A fair market would total exactly 100%. A spread priced -110 on each side totals 104.8%, and that extra 4.8% is the sportsbook's cut — the vig.
That is the bar you clear before you make a dollar, and most bettors never do. The cut is not the same everywhere, so the same bet at a different book can be a lower bar.
Common questions
What does +200 mean?
+200 means a $100 bet pays $200 in profit if it wins. For the price to break even, the bet has to win 33.3% of the time. +200 underdogs win less than half the time but pay 2-to-1.
How do I convert American odds to decimal?
Underdog price like +150: divide by 100 and add 1, giving 2.50. Favorite price like -150: divide 100 by 150 and add 1, giving 1.667.