If you're new to sports betting, odds probably look like a foreign language. Don't worry — once you understand the logic, they're actually pretty simple. Think of odds as the betting world's way of showing two things: who's likely to win, and how much you'll make if you're right.
Every betting odd tells you the same fundamental information:
The key principle: lower odds = higher probability = smaller payout. A heavy favorite might be -500 (bet $500 to win $100), while a massive underdog could be +800 (bet $100 to win $800).
American odds are what you'll see at every US sportsbook. They use positive and negative numbers, and once you get the hang of them, they're quite logical.
Negative odds tell you how much you need to bet to win $100.
| Odds | To Win $100, Bet | $50 Bet Wins | Total Return on $50 |
|---|---|---|---|
| -110 | $110 | $45.45 | $95.45 |
| -150 | $150 | $33.33 | $83.33 |
| -200 | $200 | $25 | $75 |
| -500 | $500 | $10 | $60 |
Formula for negative odds: (Bet Amount) ÷ (Odds without minus sign) × 100 = Profit
Positive odds tell you how much profit you'll make on a $100 bet.
| Odds | $100 Bet Wins | $50 Bet Wins | Total Return on $50 |
|---|---|---|---|
| +110 | $110 | $55 | $105 |
| +150 | $150 | $75 | $125 |
| +200 | $200 | $100 | $150 |
| +500 | $500 | $250 | $300 |
Formula for positive odds: (Bet Amount) × (Odds) ÷ 100 = Profit
Decimal odds are popular worldwide and frankly much easier to work with. They show your total return (including your original stake) for every $1 bet.
If you see odds of 2.50, a $100 bet would return $250 total ($150 profit + $100 stake back).
| Decimal Odds | $100 Bet Returns | Profit | American Equivalent |
|---|---|---|---|
| 1.50 | $150 | $50 | -200 |
| 1.91 | $191 | $91 | -110 |
| 2.00 | $200 | $100 | +100 |
| 2.50 | $250 | $150 | +150 |
| 6.00 | $600 | $500 | +500 |
Formula: (Bet Amount) × (Decimal Odds) = Total Return
The beauty of decimal odds is their simplicity. Want to know what a $73 bet at 3.25 odds would return? Just multiply: $73 × 3.25 = $237.25 total.
Fractional odds look like 3/1 or 9/2 and represent profit relative to your stake. They're less common in US sports betting but you'll see them occasionally, especially for horse racing.
The format is Profit/Stake. So 3/1 means you profit $3 for every $1 you bet.
| Fractional Odds | Meaning | $100 Bet Returns | American Equivalent |
|---|---|---|---|
| 1/2 | Win $1 for every $2 bet | $150 total | -200 |
| 1/1 (Evens) | Win $1 for every $1 bet | $200 total | +100 |
| 3/2 | Win $3 for every $2 bet | $250 total | +150 |
| 5/1 | Win $5 for every $1 bet | $600 total | +500 |
| 9/2 | Win $9 for every $2 bet | $550 total | +450 |
Formula: (Bet Amount) × (First Number ÷ Second Number) = Profit
Sometimes you'll want to convert between formats to better understand value or compare across sportsbooks. Here are the key conversions:
Examples: +150 = (150÷100) + 1 = 2.50 | -150 = (100÷150) + 1 = 1.67
Examples: 2.50 = (2.50-1) × 100 = +150 | 1.67 = -100÷(1.67-1) = -149
Every odd implies a probability of that outcome happening. Understanding this helps you identify whether you think a bet offers good value.
American Odds:
Decimal Odds: (1 ÷ Decimal Odds) × 100
| American Odds | Decimal Odds | Implied Probability | Meaning |
|---|---|---|---|
| -110 | 1.91 | 52.4% | Should win ~5 out of 10 times |
| -200 | 1.50 | 66.7% | Should win ~2 out of 3 times |
| +150 | 2.50 | 40.0% | Should win ~2 out of 5 times |
| +300 | 4.00 | 25.0% | Should win ~1 out of 4 times |
Value betting is when you think an outcome is more likely than the odds suggest. If you think the Warriors have a 60% chance to win, but the odds imply only 45%, that's potential value.
If you add up the implied probabilities for both sides of a bet, they usually total more than 100%. This extra percentage is called the "vig" or "juice" — it's how sportsbooks profit.
Typical vig ranges:
Lower vig means better value for bettors. This is why shopping lines matters — that -105 line is significantly better than -110.
Different sportsbooks often offer different odds on the same game. These small differences add up significantly over time.
| Sportsbook | Lakers Spread | $100 Bet Profit | Annual Difference* |
|---|---|---|---|
| Book A | -5.5 (-115) | $86.96 | -$260 |
| Book B | -5.5 (-110) | $90.91 | -$130 |
| Book C | -5.5 (-105) | $95.24 | $0 |
*Based on 100 bets annually with 50% win rate
Getting -105 instead of -115 saves you $130 per year on just 100 bets. That's why serious bettors maintain accounts at multiple sportsbooks.
Live odds change constantly during games based on what's happening. Understanding how to read them quickly is crucial for in-game betting.
Live betting offers the same bet types as pre-game, but with constantly updating odds:
The key to successful live betting is having a plan before the game starts. Don't chase bad beats or let the excitement of the moment drive your decisions.
Now that you understand odds, explore our other guides to build your betting knowledge.
Explore all IYROT guides