How to Read Prop Betting Odds: Complete Guide for Beginners (2025)

Understanding how to read prop betting odds is the first step to making informed bets on player props, game props, and other proposition markets. Whether you are betting on NFL passing yards, NBA points, or MLB strikeouts, knowing how to interpret odds formats, calculate payouts, and understand implied probability will help you make better decisions and avoid costly mistakes.

This guide will walk you through the three main odds formats used in US sportsbooks—American, decimal, and fractional—and show you how to read prop betting odds for different market types. You will learn how to calculate payouts, convert odds to implied probability, and spot value in prop markets. By the end, you should be comfortable reading any prop bet odds and understanding what they mean for your potential profit and risk.

Sports betting is for adults 21+ only in legal US states. Always bet responsibly and never wager more than you can afford to lose.

The Three Main Odds Formats Explained

US sportsbooks typically offer odds in three formats: American, decimal, and fractional. Most US bettors use American odds, but it helps to understand all three.

American Odds (Moneyline Format)

American odds, also called moneyline odds, are the default format for most US sportsbooks. They use positive and negative numbers to show how much you need to risk or how much you can win based on a $100 bet.

Negative odds (favorites):

• Example: -110, -150, -200
• Shows how much you need to risk to win $100
• -110 means risk $110 to win $100
• -200 means risk $200 to win $100

Positive odds (underdogs):

• Example: +120, +150, +300
• Shows how much you win if you risk $100
• +120 means risk $100 to win $120
• +300 means risk $100 to win $300

Most player props use odds close to even money, like -110 or -105, because over/under markets are designed to attract balanced action on both sides.

Decimal Odds (European Format)

Decimal odds are popular in Europe and show your total return for every $1 wagered, including your stake.

Examples:

• 1.91 means you get $1.91 back for every $1 bet (including your original stake)
• 2.50 means you get $2.50 back for every $1 bet

To calculate profit, subtract 1 from the decimal odds. For example, 2.50 decimal odds means 1.50 profit per $1 wagered.

Conversion:

• American -110 = Decimal 1.91
• American +150 = Decimal 2.50

Fractional Odds (UK Format)

Fractional odds are traditional in the UK and show profit relative to stake.

Examples:

• 10/11 means you win $10 for every $11 wagered
• 3/2 means you win $3 for every $2 wagered

Conversion:

• American -110 = Fractional 10/11
• American +150 = Fractional 3/2

Most US bettors stick with American odds, but knowing how to convert between formats is useful when comparing lines across different sportsbooks or international markets.

Reading Player Prop Odds (Over/Under Markets)

The most common prop bet format is over/under, where you bet whether a player will go over or under a specific line.

Example: NFL Passing Yards Prop

Market display:

• Patrick Mahomes passing yards
• Over 275.5 at -110
• Under 275.5 at -110

How to read it:

• Line: 275.5 yards (half-point to avoid ties)
• Over -110: If Mahomes throws 276+ yards, you win. Risk $110 to win $100.
• Under -110: If Mahomes throws 275 or fewer yards, you win. Risk $110 to win $100.

Why both sides are -110:

The sportsbook sets both sides at -110 to attract balanced action. If more money comes in on the over, the book might adjust odds to Over -115 / Under -105 to encourage more under bets.

Example: NBA Points Prop

Market display:

• LeBron James points
• Over 25.5 at -115
• Under 25.5 at -105

How to read it:

• Over -115: Risk $115 to win $100 if LeBron scores 26+ points
• Under -105: Risk $105 to win $100 if LeBron scores 25 or fewer points

Why the odds are different:

The under is slightly more favorable (-105 vs -115), which suggests the sportsbook expects more money on the over or believes the true probability leans slightly under.

Understanding Half-Point Lines vs Whole Numbers

Most props use half-point lines (e.g., 275.5, 25.5) to avoid pushes. With a half-point line, the result is always clear: either over or under.

Some props use whole numbers (e.g., 275, 25). If the result lands exactly on the line, the bet is typically graded as a push, and your stake is refunded. Always check your sportsbook's rules for how pushes are handled.

How to Calculate Payouts From Prop Odds

American Odds Payout Formula

For negative odds, use this formula:

Payout = Stake / (Odds / 100)

Example: -110 odds with $110 stake

• Payout = $110 / (110 / 100) = $110 / 1.10 = $100 profit
• Total return = $110 stake + $100 profit = $210

For positive odds, use this formula:

Payout = Stake × (Odds / 100)

Example: +150 odds with $100 stake

• Payout = $100 × (150 / 100) = $100 × 1.50 = $150 profit
• Total return = $100 stake + $150 profit = $250

Quick Reference Payout Table

Odds	Stake	Profit	Total Return
-110	$110	$100	$210
-150	$150	$100	$250
+100	$100	$100	$200
+150	$100	$150	$250
+200	$100	$200	$300

Using a Calculator for Complex Stakes

For non-standard stakes or complex odds, use a prop bet calculator to instantly calculate payouts and profit.

Understanding Implied Probability

Implied probability converts odds into a percentage chance of winning. It shows you what the sportsbook thinks the likelihood of your bet is, including the vig.

Formula for American Odds

For negative odds:

Implied Probability = Risk / (Risk + Win)

Example: -110 odds

• Implied Probability = 110 / (110 + 100) = 110 / 210 = 52.4 percent

For positive odds:

Implied Probability = 100 / (100 + Odds)

Example: +150 odds

• Implied Probability = 100 / (100 + 150) = 100 / 250 = 40 percent

Why Implied Probability Matters for Finding Value

Implied probability helps you compare the market's estimate to your own projection. If you think a player has a 55 percent chance of going over a line, but the market implies only 52.4 percent, you may have found positive expected value.

This is the foundation of prop betting strategy: finding situations where your projection is better than the market's implied probability.

How Vig Affects Implied Probability

On any two-sided market, the combined implied probabilities will add up to more than 100 percent. The extra percentage is the vig that the sportsbook keeps as profit.

Example: Both sides at -110

• Over implied probability: 52.4 percent
• Under implied probability: 52.4 percent
• Total: 104.8 percent
• Vig: 4.8 percent

To find the fair probability without vig, you can use a no-vig calculator or manually adjust the probabilities to sum to 100 percent.

Reading Yes/No Props and Anytime Scorer Odds

Not all props are over/under. Some are yes/no markets or specific event props.

Anytime Touchdown Scorer Example

Market display:

• Travis Kelce anytime touchdown scorer
• Yes +140
• No -180

How to read it:

• Yes +140: Risk $100 to win $140 if Kelce scores at least one touchdown
• No -180: Risk $180 to win $100 if Kelce does not score a touchdown

Implied probability:

• Yes: 100 / (100 + 140) = 41.7 percent
• No: 180 / (180 + 100) = 64.3 percent
• Total: 106 percent (6 percent vig)

First Touchdown Scorer vs Anytime Touchdown Scorer

• First touchdown scorer: Higher odds, lower probability, bet only wins if player scores the first touchdown of the game
• Anytime touchdown scorer: Lower odds, higher probability, bet wins if player scores at any point in the game

Always check which market you are betting before placing a wager.

Common Mistakes When Reading Prop Odds

Confusing Risk vs Win on Negative Odds

Many beginners see -110 and think they only need to bet $10 to win $110. In reality, -110 means you need to risk $110 to win $100.

Always check whether the number represents your risk or your potential win.

Not Accounting for Vig When Comparing Lines

Vig makes even-money bets slightly unfavorable. At -110, you need to win 52.4 percent of your bets just to break even, not 50 percent.

Always account for vig when evaluating whether a bet offers value.

Misreading Half-Point Lines

A half-point can make a huge difference in whether your bet wins or loses. Always double-check the exact line before placing a bet.

For more on common prop betting mistakes, see our Common Prop Betting Mistakes guide.

Frequently Asked Questions

What do +110 and -110 mean in prop betting?

+110 means you win $110 if you risk $100. -110 means you need to risk $110 to win $100. Negative odds indicate favorites or higher probability outcomes, while positive odds indicate underdogs or lower probability outcomes.

How do I calculate my payout from prop odds?

For negative odds, divide your stake by (odds / 100). For positive odds, multiply your stake by (odds / 100). Most sportsbooks and calculators will do this automatically for you.

What is implied probability and why does it matter?

Implied probability converts odds into a percentage chance of winning. It helps you compare the sportsbook's estimate to your own projection and identify value bets.

Why are both sides of a prop usually -110?

Sportsbooks set both sides at -110 to attract balanced action and guarantee a profit from the vig. If more money comes in on one side, the odds will adjust to encourage bets on the other side.

What is vig and how does it affect my prop bets?

Vig, also called juice or hold, is the sportsbook's built-in edge. It is the reason both sides of a prop add up to more than 100 percent implied probability. Vig means you need to win more than 50 percent of even-money bets to break even.

Can I use a calculator to read prop odds?

Yes, a prop bet calculator can instantly convert odds to implied probability, calculate payouts, and help you identify value.