How to Read Betting Odds: The Complete Beginner's Guide

You open DraftKings, tap on the Eagles game, and see this:

Saquon Barkley Over 89.5 Rushing Yards: -115

What does -115 even mean? Is that good? How much would you win? And why is there a minus sign?

If you've ever stared at a sportsbook feeling confused, you're not alone. Betting odds look like they were designed to intimidate beginners. But here's the good news: once you understand the pattern, you'll read odds as easily as a box score.

By the end of this guide, you'll know exactly what those numbers mean, how to calculate your payout, and—most importantly—how to spot when the odds are actually in your favor.

Let's break it down.

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The Three Odds Formats (And Which One Matters)

Sportsbooks around the world display odds in three different formats:

Format	Example	Where It's Used
American	-110, +200	United States
Decimal	1.91, 3.00	Europe, Australia, Canada
Fractional	10/11, 2/1	United Kingdom

If you're betting in the US—on DraftKings, FanDuel, BetMGM, or any major sportsbook—you'll see American odds by default. That's what we'll focus on.

We'll cover decimal and fractional conversions later, but master American odds first. Everything else becomes easy after that.

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American Odds Explained: The Two Rules

American odds always have a plus (+) or minus (-) sign. That sign tells you everything you need to know.

Rule 1: Minus (-) Odds = The Favorite

Negative odds mean the outcome is more likely to happen. The number tells you how much you need to risk to win $100.

The bigger the negative number, the heavier the favorite:

• -110: Slight favorite (risk $110 to win $100)
• -200: Solid favorite (risk $200 to win $100)
• -500: Heavy favorite (risk $500 to win $100)

Rule 2: Plus (+) Odds = The Underdog

Positive odds mean the outcome is less likely. The number tells you how much you win on a $100 bet.

The bigger the positive number, the bigger the underdog:

• +110: Slight underdog (win $110 on a $100 bet)
• +200: Moderate underdog (win $200 on a $100 bet)
• +500: Big underdog (win $500 on a $100 bet)

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The Magic Number: -110

You'll see -110 everywhere. It's the default odds for most point spreads and totals. But why?

This is where sportsbooks make their money.

At -110 odds, you risk $110 to win $100. If you bet both sides of a game at -110 each, you'd wager $220 total to guarantee a $210 return—losing $10 to the house no matter what.

That $10 difference is called the vig (short for vigorish) or juice. It's the sportsbook's built-in commission on every bet.

Here's why this matters for you: at -110 odds, you need to win 52.4% of your bets just to break even. Not 50%—52.4%. That extra 2.4% is the house edge.

This is why "picking winners" isn't enough. You need to find bets where the true probability exceeds the implied probability—that's where positive expected value comes in.

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How to Calculate Your Payout

You don't always bet exactly $100. Here's how to calculate payouts for any stake.

For Positive (+) Odds

Profit = (Stake × Odds) ÷ 100

Example: $50 bet at +200

• Profit = ($50 × 200) ÷ 100 = $100
• Total return = $50 stake + $100 profit = $150

For Negative (-) Odds

Profit = Stake ÷ (Odds ÷ 100)

Example: $50 bet at -150

• Profit = $50 ÷ (150 ÷ 100) = $50 ÷ 1.5 = $33.33
• Total return = $50 stake + $33.33 profit = $83.33

Don't want to do the math yourself? Use our Fair Odds Calculator to instantly see payouts, implied probability, and true odds.

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Implied Probability: The Secret Behind the Odds

Here's where things get interesting.

Every set of odds implies a probability—the sportsbook's estimate of how likely an outcome is to happen. Understanding this is the single most important skill in sports betting.

Converting Odds to Implied Probability

For Negative (-) Odds:

Implied Probability = Odds ÷ (Odds + 100)

Example: -150 odds

• 150 ÷ (150 + 100) = 150 ÷ 250 = 60%

For Positive (+) Odds:

Implied Probability = 100 ÷ (Odds + 100)

Example: +200 odds

• 100 ÷ (200 + 100) = 100 ÷ 300 = 33.3%

Quick Reference: Common Odds → Probability

American Odds	Implied Probability	Decimal Odds
-500	83.3%	1.20
-300	75.0%	1.33
-200	66.7%	1.50
-150	60.0%	1.67
-110	52.4%	1.91
+100 (Even)	50.0%	2.00
+150	40.0%	2.50
+200	33.3%	3.00
+300	25.0%	4.00
+500	16.7%	6.00

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Putting It All Together: A Real NFL Example

Let's look at an actual player prop and break down exactly what the odds are telling us.

Breaking Down the Odds

The line is -115. Here's what that tells us:

1. It's a slight favorite (negative odds)
2. Risk $115 to win $100
3. Implied probability: 53.5% (115 ÷ 215)

Now here's where it gets interesting. The sportsbook is saying this prop has about a 53.5% chance of hitting. But Barkley has actually cleared this line in 71% of his recent games.

That gap—between what the odds imply (53.5%) and what the data suggests (71%)—is called the edge. Finding these gaps consistently is how sharp bettors profit long-term.

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The Vig: Why Both Sides Add Up to More Than 100%

Here's something that confuses a lot of beginners. If you look at a point spread:

• Eagles -3.5: -110
• Steelers +3.5: -110

Both sides are -110. That means:

• Eagles implied probability: 52.4%
• Steelers implied probability: 52.4%
• Total: 104.8%

Wait—that's more than 100%. That's not possible, right?

This "extra" percentage is the vig. It's how sportsbooks guarantee profit regardless of the outcome. The more the implied probabilities exceed 100%, the more juice the book is charging.

A 104.8% total (standard -110/-110 lines) means about a 4.5% vig. Some books offer reduced juice at -105, which drops the total to ~102.4%—saving you money over time.

Pro tip: Use our Fair Odds Calculator to strip out the vig and see the true "no-juice" odds. This helps you compare lines across sportsbooks and find the best value.

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Converting to Decimal and Fractional Odds

If you bet internationally or use certain platforms, you'll encounter other formats. Here's how to convert:

American to Decimal

For Positive (+) Odds:

Decimal = (American ÷ 100) + 1

Example: +200 → (200 ÷ 100) + 1 = 3.00

For Negative (-) Odds:

Decimal = (100 ÷ |American|) + 1

Example: -150 → (100 ÷ 150) + 1 = 1.67

Understanding Decimal Odds

Decimal odds show your total return per $1 bet (stake + profit).

• 2.00: Double your money (equivalent to +100/Even)
• 1.50: Win half your stake as profit (equivalent to -200)
• 3.00: Triple your money (equivalent to +200)

Fractional Odds (UK Style)

Fractional odds show profit relative to stake. 2/1 (read "two to one") means you win $2 for every $1 bet—equivalent to +200 American.

Common conversions:

• 10/11 = -110 American
• Evens (1/1) = +100 American
• 2/1 = +200 American
• 5/1 = +500 American

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Common Mistakes Beginners Make

Mistake 1: Thinking Plus Odds Are Always "Good"

+300 looks attractive—you could triple your money! But if the actual probability is only 20%, you're getting ripped off. The sportsbook is implying 25% (100 ÷ 400), which is already generous.

The fix: Always convert odds to implied probability. Then ask: "Do I think this outcome is MORE likely than the odds suggest?"

Mistake 2: Ignoring Line Movement

If a line moves from -110 to -130, that's significant. Sharp money (professional bettors) likely hit that side. Odds aren't static—they reflect where the money is going.

The fix: Pay attention to opening lines vs. current lines. Big moves often signal value on the other side, or sharp action you might want to follow.

Mistake 3: Not Shopping for Best Odds

One book has Barkley Over 89.5 at -115. Another has it at -105. That 10-cent difference might seem small, but over hundreds of bets, it adds up to thousands of dollars.

The fix: Have accounts at multiple sportsbooks. Always compare odds before placing a bet. The extra 60 seconds can dramatically improve your long-term results.

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Now That You Can Read Odds, What's Next?

Understanding odds is the foundation. But reading odds is just step one—finding value is where the real skill comes in.

Here's your roadmap:

1. Master implied probability. Use our Fair Odds Calculator until conversions become second nature.
2. Learn about expected value. Read our guide on what positive EV means and why it matters more than picking winners.
3. Understand edge. Our article on finding betting edge explains how to spot when odds are mispriced.
4. Manage your bankroll. Even +EV bets can lose. Learn how the Kelly Criterion protects your bankroll while maximizing growth.

Or, skip the learning curve entirely. TrueEdge does the heavy lifting—analyzing thousands of props to surface the ones with real mathematical edge, explained in plain English.

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Frequently Asked Questions

Q: What does -110 mean in betting?
A: -110 means you need to risk $110 to win $100. This is the standard "vig" or "juice" that sportsbooks charge on most point spread and totals bets. The implied probability of -110 odds is 52.4%, which is why you need to win more than half your bets to be profitable.

Q: What does +200 mean in betting?
A: +200 means you win $200 profit on a $100 bet. Plus (+) odds indicate an underdog and show how much profit you make on a $100 wager. The implied probability of +200 odds is 33.3%, meaning the sportsbook believes this outcome has about a 1-in-3 chance of happening.

Q: How do you calculate betting odds payout?
A: For positive (+) odds: Profit = (Stake × Odds) ÷ 100. For negative (-) odds: Profit = Stake ÷ (Odds ÷ 100). For example, a $50 bet at +200 pays $100 profit. A $50 bet at -150 pays $33.33 profit.

Q: What is implied probability in betting?
A: Implied probability is the win percentage suggested by the betting odds. It tells you how often a bet needs to win to break even. For positive odds: 100 ÷ (odds + 100). For negative odds: odds ÷ (odds + 100). Understanding implied probability is essential for finding value bets.

Q: Why are betting odds negative?
A: Negative odds indicate a favorite—the outcome the sportsbook believes is more likely to happen. The negative number shows how much you must risk to win $100. The bigger the negative number, the heavier the favorite.

Q: What is the vig in sports betting?
A: The vig (short for vigorish, also called "juice") is the sportsbook's built-in commission on every bet. It's why both sides of a bet don't add up to 100%. The standard vig is -110 on each side, giving the sportsbook roughly a 4.5% edge.

Q: How do I convert American odds to decimal odds?
A: For positive American odds: Decimal = (American ÷ 100) + 1. For negative American odds: Decimal = (100 ÷ |American|) + 1. For example, +200 = 3.00 decimal, and -150 = 1.67 decimal.

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The Bottom Line

Reading betting odds isn't complicated once you know the rules:

• Minus (-) odds: How much you risk to win $100
• Plus (+) odds: How much you win on a $100 bet
• Implied probability: The hidden win percentage behind every line
• The vig: Why the house always has an edge (until you find your own)

Now you're ready to look at odds differently. Not just "who's going to win," but "is this price accurate?" That shift in thinking is what separates casual bettors from sharp ones.

Ready to put this knowledge to work? Try our Fair Odds Calculator to practice converting odds and finding true probabilities—or join the TrueEdge waitlist to get AI-powered picks with the edge already calculated for you.