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How to Read Betting Odds: American, Decimal and Implied Probability (2026)

Learn how to read betting odds at BetOnline: American, decimal and fractional formats, favorites and underdogs, plus how to convert odds to implied probability. 21+.

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Reading odds is the first skill every sports bettor needs. In this guide we explain American, decimal and fractional odds, how favorites and underdogs are priced and how to turn any price into an implied probability, so you can read the BetOnline board with confidence.

American Odds: Favorites and Underdogs

American odds use a plus or minus sign. A minus number, like -150, shows how much you stake to win $100, so the favorite costs more to back. A plus number, like +130, shows what a $100 stake returns, so the underdog pays more for the same stake. The bet slip converts this into a clear payout before you confirm.

Decimal and Fractional Formats

Decimal odds show the total return per unit staked, so 2.50 returns 2.5 times your stake including the stake. Fractional odds, common in racing, show profit against stake, so 3/1 returns three units of profit for every one staked. BetOnline lets you focus on the format you read most easily.

Converting Odds to Implied Probability

Implied probability is the chance a price suggests. For a minus favorite, divide the odds by the odds plus 100. For a plus underdog, divide 100 by the odds plus 100. Comparing implied probability with your own read is how sharp bettors find value on the board.

Reading a Live Odds Board

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Odds move with news, money and, in live betting, the score and clock. A shortening price means more support for that side, while a drifting price means less. BetOnline keeps the confirmation step visible so you can lock a price before the market moves again.

Frequently Asked Questions

What do plus and minus mean in betting odds?
A minus number shows how much you stake to win $100 on a favorite, and a plus number shows what a $100 stake returns on an underdog. The bet slip always shows your exact payout before you confirm.
How do I convert odds to a percentage?
For a minus price, divide the odds by the odds plus 100. For a plus price, divide 100 by the odds plus 100. The result is the implied probability the price suggests.
Which odds format is best?
No format is better; they express the same price. Pick the one you read fastest, whether American, decimal or fractional, and the payout stays the same. Ready to bet? Open the BetOnline sportsbook and start with a market you understand. 21+, bet responsibly.