What is Implied Probability in Sports Betting?

Introduction

Implied probability is the hidden math behind betting odds. It tells you how likely a sportsbook thinks an outcome is — and whether your bet has real value.

If you’re serious about betting smarter (and not just guessing), learning how to calculate implied probability is a game-changer.

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➕ Positive Odds (+)

For underdogs, odds are shown with a + sign (e.g., +200). This means you’d win $200 on a $100 bet.

To convert this to implied probability:

Formula:

Implied Probability = 100 / (Odds + 100)

Example:

+200 → 100 / (200 + 100) = 0.333 = 33.3%

This means the sportsbook believes there’s a 33.3% chance of this outcome happening.

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➖ Negative Odds (–)

For favorites, odds come with a – sign (e.g., -150). This means you need to bet $150 to win $100.

To convert to probability:

Formula:

Implied Probability = Odds / (Odds + 100)

Example:

-150 → 150 / (150 + 100) = 0.6 = 60%

The sportsbook believes this outcome happens 60% of the time.

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Why Implied Probability Matters

• Helps you spot +EV (positive expected value) bets
• Lets you compare your prediction vs. the sportsbook’s
• A key part of any data-driven or AI-powered betting strategy

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Pro Tip from BetMetrics

Our models constantly compare implied probability to actual win probability based on data and trends. When our internal win chance is higher than the book’s implied probability, we flag that bet as a smart value play.

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Want to Practice?

Use our free Implied Probability Calculator (coming soon!) to plug in odds and see the real math behind the line.