Dimers Summer School: How to Read Sports Betting Odds and Calculate Implied Probability

Odds are the backbone of sports betting—they tell you both the likelihood of an outcome and how much you could win. If you’re new to betting or want to make smarter wagers, understanding odds is the first step.

As part of our Dimers.com Summer School series, let’s break it down in simple terms, then explore how to calculate something called implied probability, which can help you find better value bets.

How to Read Betting Odds

Imagine you want to bet $100 on the Yankees to beat the Blue Jays. The sportsbook lists:

• Yankees: -135 (favorites)

• Blue Jays: +110 (underdogs)

Here’s what that means:

• Bet $100 on Yankees (-135) → Win $74.07 profit if they win, for a total payout of $174.07.

• Bet $100 on Blue Jays (+110) → Win $110 profit if they win, for a total payout of $210.

The minus sign means you have to wager more to win $100 (favorite), while the plus sign means you win more than your bet if your team wins (underdog).

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What Is Implied Probability?

Odds aren’t just numbers—they reflect the implied probability of an event happening.

Implied probability is the percentage chance a sportsbook believes an outcome will occur, based on the odds. By calculating it yourself, you can decide if a bet offers good value compared to your own predictions.

MORE: Best Player Props for Today

How to Calculate Implied Probability

There’s a simple formula for converting odds into implied probability:

• Favorites (-): Odds / (Odds + 100) × 100

• Underdogs (+): 100 / (Odds + 100) × 100

Using our Yankees vs. Blue Jays example:

• Yankees (-135): 135 / (135 + 100) × 100 = 57.4%

• Blue Jays (+110): 100 / (110 + 100) × 100 = 47.6%

Why the Percentages Add to More Than 100%

You might notice 57.4% + 47.6% = 105%. That extra 5% isn’t a math mistake—it’s the vig (short for vigorish), which is the sportsbook’s built-in commission.

Knowing the vig helps you understand how much of a cut the sportsbook is taking and whether you’re getting fair value.

MORE: Dimers' Best Bets for Today

Applying Implied Probability Beyond Moneylines

While implied probability is common in moneyline bets, you can also use it for futures, player props, and other betting markets.

By comparing implied probability to your own predictions, you can spot when a sportsbook’s line might be off—and take advantage.

Key Takeaways

• Odds show both payout potential and likelihood of an outcome.

• Implied probability helps you judge if a bet is worth taking.

• The vig explains why total percentages exceed 100%.

• You can calculate it manually or use an odds calculator at Dimers.com for quick results.

The more you understand the math behind the odds, the more strategic—and potentially profitable—your sports betting decisions will be.

Finding sportsbooks for the best odds and bonus offers is easy on the Dimers Best Betting Sites page. Find the best offer in your state and click through to sign up. The process is fast and easy for most sportsbooks with registration completed in less than a couple of minutes.

Responsible Gambling

Remember to please gamble responsibly. If you sense that you're taking your luck too far, know when to call it quits and don't be afraid to seek assistance. Keep in mind that gambling is all about having a fantastic experience! If you or someone you know is grappling with gambling issues, reach out to 1-800-GAMBLER for crisis counseling and support.