Implied Odds in Sports Betting, Explained
Implied odds in sports betting is the win probability baked into a price. How to convert American, decimal, and fractional odds and strip the vig.
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Ask a sportsbook “how likely is this?” and it never answers in plain English — it answers with a price. Implied odds is that answer decoded: the win probability baked into a betting line. A price of -150 is the book saying 60%; +200 is the book saying 33.3%. Turning every price back into a percentage is what lets you hold the book’s number next to your own and bet only when yours is higher. (This is a different animal from implied odds in poker, which we separate at the end.)
Reading American prices
American odds split into negatives (favorites) and positives (underdogs), each with its own formula.
Favorites (negative): implied % = odds ÷ (odds + 100). For -150: 150 ÷ 250 = 60.0%.
Underdogs (positive): implied % = 100 ÷ (odds + 100). For +200: 100 ÷ 300 = 33.3%.
The standard juice line of -110 lands at 110 ÷ 210 = 52.38% — worth memorizing, since it’s the reference for the vig below.
Decimal and fractional
Decimal is the easiest: implied % = 1 ÷ decimal. So 1.91 gives 52.4% (the decimal twin of -110) and 2.50 gives 40.0%.
Fractional odds, common in the UK, use denominator ÷ (numerator + denominator). So 5/1 gives 1 ÷ 6 = 16.7% and evens (1/1) gives 50.0%.
| Format | Example | Implied |
|---|---|---|
| American (fav) | -150 | 60.0% |
| American (dog) | +200 | 33.3% |
| American (juice) | -110 | 52.38% |
| Decimal | 2.50 | 40.0% |
| Fractional | 5/1 | 16.7% |
The catch: why two sides break 100%
Price a game with both sides at -110. Each implies 52.38%, so together they imply 52.38% + 52.38% = 104.76%. Probabilities can’t exceed 100% — that extra 4.76% is the sportsbook’s margin, the vig (also juice, or overround). It’s the structural house edge, the same reason a room profits over time even when skill meets skill.
To find the market’s genuine opinion, normalize back to 100% by dividing each side by the total. Both -110 sides: 52.38% ÷ 104.76% = 50.0% — a clean coin flip. On a lopsided game like -200 (66.67%) vs +170 (37.04%), summing to 103.71%, the no-vig favorite is 66.67% ÷ 103.71% = 64.3%.
Where the money actually is
Converting odds is idle unless you act on the gap. The loop is simple: convert the price to a percentage, strip the vig, then compare to your own estimate. If you rate the outcome likelier than the fair price says, you have positive expected value.
A book offers +150 on a team — implied 100 ÷ 250 = 40%. If your model says they win 45%, you’re getting paid like a 40% shot on a 45% event: a value bet. If your read is 35%, pass. It’s the same equity-versus-price logic behind pot odds: never commit chips unless your win rate beats the price you’re paying.
One phrase, two games
The term collides, and the mix-up causes real confusion. In sports betting, implied odds is a win probability decoded from a price — a conversion, nothing more. In poker, implied odds is the extra chips you expect to win on future streets once your draw completes — a forward-looking read on future action, not a probability at all. A player calling a flush draw is weighing how much more the river will pay; a bettor talking implied odds is just reading a number off the screen. For the conversion skill itself, keep going with implied probability and the full poker odds and math hub.
Frequently asked
How do you calculate implied odds from American odds?
For a negative (favorite) price, divide the number by itself plus 100: -150 becomes 150 / (150 + 100) = 60%. For a positive (underdog) price, divide 100 by the number plus 100: +200 becomes 100 / (200 + 100) = 33.3%.
What is the vig and how does it affect implied odds?
The vig is the sportsbook's built-in margin. Because two -110 sides each imply 52.38%, they sum to about 104.8% — the extra 4.8% is the house edge. Strip it out to get the true no-vig probability.
Is implied odds the same in poker and sports betting?
No. In sports betting, implied odds means the probability baked into a price. In poker, implied odds means the extra chips you expect to win on later streets when your draw hits. Same phrase, two different ideas.