Odds converter and no-vig calculator
Type a price in any format to see it in the others, including the win rate you need to break even. Then enter both sides of a market to see the book's hold and the fair, vig-free price for each side.
American · decimal · implied probability
Type in any box; the others follow.
No-vig calculator
Both sides of a two-way market (spread, total or moneyline).
| Side | Price | Fair prob. | Fair price |
|---|---|---|---|
| A | -110 | 50.00% | +100 |
| B | -110 | 50.00% | +100 |
Fair prices use proportional vig removal (each side scaled so the two add to 100%). A price better than the fair price elsewhere is a positive-value bet if this market is efficient.
Runs entirely in your browser; nothing you type is sent anywhere. For information only: not betting advice. 21+.
The formulas
- American to decimal: positive odds: 1 + odds / 100. Negative odds: 1 + 100 / |odds|. So +150 is 2.50 and -110 is 1.909.
- Implied probability: negative odds: |odds| / (|odds| + 100). Positive odds: 100 / (odds + 100). Or simply 1 / decimal odds.
- Hold: add both sides' implied probabilities to get the overround; the book's theoretical hold is 1 - 1 / overround.
- No-vig fair probability: each side's implied probability divided by the overround.
Reading a market
A standard -110 / -110 market holds about 4.5%. Reduced-juice markets at -105 / -105 hold about 2.4%, which is a large difference over a season of bets. When one side is +100 at one book and the fair price from another market is -105, that gap is the value.
Questions
How do I convert American odds to implied probability?
For negative odds, divide the odds by the odds plus 100 (using the absolute value): -110 is 110 / 210 = 52.4%. For positive odds, divide 100 by the odds plus 100: +150 is 100 / 250 = 40%. That's also the win rate you need to break even at that price.
What is the vig (juice)?
The bookmaker's margin. In a -110 / -110 market both sides imply 52.4%, which adds up to 104.8%. The extra 4.8% is the overround; the book's theoretical hold is about 4.5% of the money wagered.
What is a no-vig or fair price?
The price with the bookmaker's margin removed, found by scaling both sides' implied probabilities so they add up to 100%. It's the market's estimate of the true probability, and the right baseline for judging a price or measuring closing-line value.
Are decimal odds better than American odds?
They're the same information. Decimal odds include your stake (2.50 returns $2.50 per $1, including the dollar), which makes payouts and comparisons easier; American odds are standard at US sportsbooks.
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