How to Read Betting Odds: Complete Guide to Sports Odds
Complete guide to understanding American, Decimal, and Fractional odds formats
What Do Betting Odds Mean?
Betting odds communicate two crucial pieces of information:
- Your potential winnings - The profit you stand to make from a successful bet
- Implied probability - The likelihood the bookmaker assigns to that outcome occurring
Odds appear in three distinct formats depending on your location:
- American odds (e.g., +150, -200) - Standard format in the United States
- Decimal odds (e.g., 2.50, 1.50) - Common in Europe, Australia, and Canada
- Fractional odds (e.g., 3/2, 1/2) - Traditional format in the UK and Ireland
These three formats convey identical information using different presentation styles. We'll examine each format in detail.
American Odds Explained
American odds (sometimes called moneyline odds) utilize positive (+) and negative (-) numbers to indicate favorites and underdogs.
Positive Odds (+)
Positive odds display the profit amount you'll earn from a $100 wager.
+150 odds example:
- Means you win $150 profit on a $100 bet
- Bet $100, win $150 profit = $250 total return
- The + sign indicates an underdog
Calculating profit for positive odds:
Profit = (Stake × Odds) / 100
- Bet $50 at +150: ($50 × 150) / 100 = $75 profit
- Bet $20 at +200: ($20 × 200) / 100 = $40 profit
Negative Odds (-)
Negative odds indicate how much you need to wager to earn $100 in profit.
What do odds of -200 mean?
- You need to bet $200 to profit $100
- Wager $200, earn $100 profit = $300 total payout
- The - sign marks a favorite
- Larger negative numbers indicate stronger favorites (e.g., -400 is a heavier favorite than -200)
Calculating profit for negative odds:
Profit = (Stake × 100) / Absolute Value of Odds
- Bet $100 at -150: ($100 × 100) / 150 = $66.67 profit
- Bet $50 at -200: ($50 × 100) / 200 = $25 profit
Common American Odds
| Odds | Meaning | $100 Bet Profit | Type |
|---|---|---|---|
| +100 | Even money | $100 | Even |
| +150 | Win $150 per $100 | $150 | Underdog |
| +200 | Win $200 per $100 | $200 | Underdog |
| -110 | Bet $110 to win $100 | $90.91 | Favorite |
| -150 | Bet $150 to win $100 | $66.67 | Favorite |
| -200 | Bet $200 to win $100 | $50 | Favorite |
Decimal Odds Explained
Decimal odds are the easiest to understand and calculate. They show your total return (profit + stake) for every $1 bet.
2.50 odds example:
- Bet $100, total return = $100 × 2.50 = $250
- Profit = $250 - $100 stake = $150 profit
- Simple multiplication: Stake × Decimal Odds = Total Payout
Calculating Payouts with Decimal Odds
Total Payout = Stake × Decimal Odds
Profit = (Stake × Decimal Odds) - Stake
Examples:
- Bet $50 at 3.00: $50 × 3.00 = $150 total ($100 profit)
- Bet $100 at 1.50: $100 × 1.50 = $150 total ($50 profit)
- Bet $20 at 2.10: $20 × 2.10 = $42 total ($22 profit)
Common Decimal Odds
| Decimal Odds | $100 Bet Payout | Profit | Implied Probability |
|---|---|---|---|
| 1.50 | $150 | $50 | 66.7% |
| 2.00 | $200 | $100 | 50% |
| 2.50 | $250 | $150 | 40% |
| 3.00 | $300 | $200 | 33.3% |
| 5.00 | $500 | $400 | 20% |
Fractional Odds Explained
Fractional odds (like 3/1, 5/2) show profit relative to stake. They're traditional in horse racing and UK betting.
3/1 odds example:
- Means you win $3 for every $1 bet
- Bet $100 at 3/1: win $300 profit + $100 stake back = $400 total
- Read as "3 to 1" or "3-to-1"
How to Read Fractional Odds
Numerator / Denominator
Profit = Stake × (Numerator / Denominator)
Examples:
- 5/1: Win $5 for every $1 bet
- 3/2: Win $3 for every $2 bet (or $1.50 per $1)
- 1/2: Win $1 for every $2 bet (or $0.50 per $1)
- Evens (1/1): Win $1 for every $1 bet
Calculating payouts:
- Bet $100 at 3/1: $100 × (3/1) = $300 profit, $400 total
- Bet $50 at 5/2: $50 × (5/2) = $125 profit, $175 total
- Bet $100 at 1/2: $100 × (1/2) = $50 profit, $150 total
Common Fractional Odds
| Fractional | Decimal | American | $100 Profit |
|---|---|---|---|
| 1/2 | 1.50 | -200 | $50 |
| Evens (1/1) | 2.00 | +100 | $100 |
| 3/2 | 2.50 | +150 | $150 |
| 2/1 | 3.00 | +200 | $200 |
| 5/1 | 6.00 | +500 | $500 |
Understanding Implied Probability
Implied probability is the likelihood of an outcome as suggested by the betting odds. It helps you understand how likely bookmakers think something is to happen.
Calculating Implied Probability
From Decimal Odds:
Implied Probability = (1 / Decimal Odds) × 100%
- 2.00 odds: (1 / 2.00) × 100% = 50%
- 3.00 odds: (1 / 3.00) × 100% = 33.3%
- 1.50 odds: (1 / 1.50) × 100% = 66.7%
From American Odds (Positive):
Implied Probability = 100 / (Odds + 100) × 100%
- +150 odds: 100 / (150 + 100) = 40%
- +200 odds: 100 / (200 + 100) = 33.3%
From American Odds (Negative):
Implied Probability = Abs(Odds) / (Abs(Odds) + 100) × 100%
- -150 odds: 150 / (150 + 100) = 60%
- -200 odds: 200 / (200 + 100) = 66.7%
Use our Implied Probability Calculator for quick conversions.
Converting Between Odds Formats
American to Decimal
Positive odds: (Odds / 100) + 1
- +150 → (150 / 100) + 1 = 2.50
- +200 → (200 / 100) + 1 = 3.00
Negative odds: (100 / Abs(Odds)) + 1
- -150 → (100 / 150) + 1 = 1.67
- -200 → (100 / 200) + 1 = 1.50
Decimal to American
If decimal ≥ 2.00: (Decimal - 1) × 100
- 2.50 → (2.50 - 1) × 100 = +150
- 3.00 → (3.00 - 1) × 100 = +200
If decimal < 2.00: -100 / (Decimal - 1)
- 1.67 → -100 / (1.67 - 1) = -150
- 1.50 → -100 / (1.50 - 1) = -200
Quick Conversion Tool
Use our Odds Converter to instantly convert between all formats.
How to Read Betting Lines
Real-World Example: NFL Game
Pittsburgh Steelers vs Kansas City Chiefs:
- Steelers: +585
- Chiefs: -760
What the odds mean:
- The Chiefs are heavy favorites with -760 odds (~88% implied probability)
- The Steelers are significant underdogs at +585 (~15% implied probability)
Betting examples:
- Bet $100 on Steelers: Win $585 profit if they pull upset (total payout $685)
- Bet $760 on Chiefs: Win $100 profit if they win (total payout $860)
The large gap between odds indicates the Chiefs are heavily favored. But remember—upsets happen in the NFL!
Real-World Example: NBA Game
Boston Celtics vs Los Angeles Lakers:
| Team | Spread | Total | Moneyline |
|---|---|---|---|
| Boston Celtics | -6 (-110) | O 217.5 (-110) | -360 |
| Los Angeles Lakers | +6 (-110) | U 217.5 (-110) | +280 |
Breaking it down:
- Spread (-6): Celtics must win by 7+ points. Both sides pay -110 (standard vig)
- Total (217.5): Combined score over or under 217.5 points, both sides -110
- Moneyline: Straight up winner. Celtics -360 ($360 to win $100) or Lakers +280 ($100 to win $280)
Notice how the moneyline has different odds while spread/total are both -110? That's because the point spread equalizes the matchup.
Point Spread Example
NBA Game:
- Lakers -5.5 (-110)
- Celtics +5.5 (-110)
What it means:
- Lakers must win by 6+ points to cover
- Celtics can lose by 5 or less (or win) to cover
- Both sides pay -110 (bet $110 to win $100)
Learn more: Spread Betting Guide
Total (Over/Under) Example
MLB Game:
- Over 8.5 (-115)
- Under 8.5 (-105)
What it means:
- Over wins if total runs ≥ 9
- Under wins if total runs ≤ 8
- Different odds on each side based on betting action
Learn more: Over/Under Betting Guide
Understanding Break-Even Percentage
Break-even percentage tells you how often you need to win for a bet to be profitable. This is a crucial concept for identifying value bets.
How to Calculate Break-Even Percentage
From American Odds:
- Positive odds: Break-even % = 100 / (Odds + 100)
- Negative odds: Break-even % = Abs(Odds) / (Abs(Odds) + 100)
Example with +200 odds:
- Break-even % = 100 / (200 + 100) = 100 / 300 = 33.33%
- Interpretation: You need to win this bet 33.33% of the time to break even
- Value bet: If YOU think it has a 40% chance of winning, it's a good bet!
Example with -150 odds:
- Break-even % = 150 / (150 + 100) = 150 / 250 = 60%
- Interpretation: You need to win this bet 60% of the time to break even
- Value bet: If YOU think it has a 65% chance of winning, it's worth betting
Using Break-Even % to Find Value
The key to profitable betting is finding bets where YOUR estimated probability exceeds the break-even percentage.
Think of a coin flip analogy:
- A coin flip has exactly 50% chance of heads
- If offered +110 odds (break-even 47.6%), it's a VALUE BET
- If offered -120 odds (break-even 54.5%), it's a BAD BET
This principle applies to sports betting with expected value calculation.
Reading Futures and Championship Odds
Futures bets are wagers on events that will happen in the future (weeks or months away). Championship odds are a common type of futures bet.
NFL Championship Futures Example
| Team | Fractional Odds | American Odds | $100 Bet Profit |
|---|---|---|---|
| Philadelphia Eagles | 6/1 | +600 | $600 |
| Kansas City Chiefs | 7/1 | +700 | $700 |
| Buffalo Bills | 7/1 | +700 | $700 |
| Baltimore Ravens | 7/1 | +700 | $700 |
| Detroit Lions | 9/1 | +900 | $900 |
| San Francisco 49ers | 15/1 | +1500 | $1,500 |
How to read this:
- The Eagles are favorites at 6/1—a $100 bet wins $600 if they win the Super Bowl
- The Chiefs, Bills, and Ravens are tied at 7/1 odds
- The 49ers are longer shots at 15/1—higher risk, but $1,500 profit on a $100 bet
Futures betting strategy: Fractional odds are commonly used for futures because most odds have a denominator of 1 (making them easier to understand). Bet early for better odds before teams prove themselves, but remember—your money is tied up for months!
Tips for Reading Odds
1. Understand the Favorite vs Underdog
- Negative odds (-) or lower decimal (< 2.0) = Favorite
- Positive odds (+) or higher decimal (> 2.0) = Underdog
2. Calculate Before Betting
Always know your exact payout before placing a bet. Don't guess!
3. Compare Odds Across Sportsbooks
The same bet can have different odds at different books. Shopping for the best line increases profit.
4. Understand the Bookmaker's Margin (Vig Meaning)
If you add up implied probabilities for all outcomes, it exceeds 100%. The excess is the bookmaker's profit margin, called the vig (vigorish) or "juice."
What does vig mean in betting?
Vig is the sportsbook's commission built into the odds. It's how bookmakers make money regardless of the outcome.
Example:
- Team A: -110 (52.4% implied probability)
- Team B: -110 (52.4% implied probability)
- Total: 104.8%
- Bookmaker edge (vig): 4.8%
The extra 4.8% is the vig. In a fair market with no vig, both sides would be +100 (50% each).
Learn more: What is Vig? | No-Vig Calculator
5. Use Odds to Find Value
Compare the implied probability to your own estimate of the true probability. If your estimate is higher, you've found a value bet.
Common Mistakes Reading Odds
❌ Mistake 1: Confusing Payout with Profit
Remember: Payout includes your stake back. Profit is what you win on top of your stake.
❌ Mistake 2: Thinking Higher Numbers Always Mean Better
In American odds, +500 pays more than +100, but in negative odds, -100 pays more than -500.
❌ Mistake 3: Mixing Up Formats
Don't confuse 2.50 decimal odds with 2/5 fractional odds. They're very different!
❌ Mistake 4: Ignoring Implied Probability
Odds aren't just about payouts - they tell you what the bookmaker thinks will happen.
Quick Reference Guide
✓ American Odds:
- Positive (+): Profit on $100 bet (underdog)
- Negative (-): Amount to bet to win $100 (favorite)
- Used in: United States
✓ Decimal Odds:
- Total return per $1 bet
- Easiest for calculations: Stake × Odds = Payout
- Used in: Europe, Australia, Canada
✓ Fractional Odds:
- Profit / Stake ratio
- Traditional format
- Used in: UK, Ireland, horse racing
✓ Key Conversions:
- Even money: +100 = 2.00 = 1/1
- -110 standard: -110 = 1.91 = 10/11
- 2-to-1: +200 = 3.00 = 2/1
Ready to find the best odds? FairOdds Terminal scans 60+ sportsbooks to find positive EV opportunities with the best odds available.
FAQ: How to Read Betting Odds
What do betting odds mean?
Betting odds tell you two things: (1) how much you'll win if your bet succeeds, and (2) the implied probability of that outcome happening. They can be displayed in three formats: American (+150, -200), Decimal (2.50, 1.50), or Fractional (3/2, 1/2).
What does +200 odds mean?
In American odds, +200 means you win $200 profit for every $100 bet. If you bet $100 at +200 odds and win, you receive $300 total ($200 profit + $100 stake back). The + sign indicates an underdog.
What does -150 odds mean?
In American odds, -150 means you must bet $150 to win $100 profit. If you bet $150 at -150 odds and win, you receive $250 total ($100 profit + $150 stake back). The - sign indicates a favorite.
Which odds format is best?
Decimal odds are easiest for calculating payouts (just multiply stake × odds). American odds are standard in the US. Fractional odds are traditional in the UK. All formats represent the same thing, just displayed differently.
How do you calculate payout from odds?
For decimal odds: Payout = Stake × Decimal Odds. For American odds: If positive, Profit = (Stake × Odds) / 100. If negative, Profit = (Stake × 100) / Abs(Odds). For fractional: Profit = Stake × (Numerator / Denominator).
What is implied probability?
Implied probability is the likelihood of an outcome as suggested by the odds. For decimal odds: Probability = 1 / Decimal Odds × 100%. For American: If positive, Probability = 100 / (Odds + 100). If negative, Probability = Abs(Odds) / (Abs(Odds) + 100).
Why do odds change?
Odds change based on betting action, new information (injuries, weather), and bookmakers balancing their books. Sharp money, public betting patterns, and breaking news all cause odds to move up or down.
Can I convert between odds formats?
Yes, all odds formats represent the same thing and can be converted. Use an odds converter tool or formulas: American to Decimal: If positive, (Odds/100) + 1. If negative, (100/Abs(Odds)) + 1. Our odds converter tool makes this easy.