American, decimal, fractional
Sports Betting Odds Explained
The three odds formats Maryland bettors will encounter, conversions between them, and how to read implied probability and the sportsbook's margin.
The Three Odds Formats
Sportsbooks express the same wager in three different formats. Maryland operators default to American odds, but most apps let you toggle in settings.
American Odds
The default format at every Maryland sportsbook. Uses positive (+) and negative (−) numbers.
- Negative: how much to risk to win $100. -180 means risk $180 to win $100.
- Positive: how much $100 wins. +160 means $100 wins $160 profit.
- Even money: written as +100 (or "Even"). $100 wagers wins $100.
Decimal Odds
Standard in Europe and on most betting exchanges. The number is your total payout per $1 wagered, including stake.
- 1.91 = wager $1, get $1.91 back if you win ($0.91 profit). Equivalent to -110.
- 2.00 = even money. $1 wagers wins $1 profit. Equivalent to +100.
- 3.00 = $1 wagers wins $2 profit. Equivalent to +200.
Fractional Odds
Standard in the UK and Ireland, especially horse racing. The number expresses profit per stake.
- 1/1 (read "evens") = wager 1, win 1. Same as +100 / 2.00.
- 5/2 = wager 2, win 5. Same as +250 / 3.50.
- 1/2 (read "odds-on") = wager 2, win 1. Same as -200 / 1.50.
Conversion Reference Table
| American | Decimal | Fractional | Implied Probability |
|---|---|---|---|
| -200 | 1.50 | 1/2 | 66.7% |
| -150 | 1.67 | 2/3 | 60.0% |
| -110 | 1.91 | 10/11 | 52.4% |
| +100 (Even) | 2.00 | 1/1 | 50.0% |
| +110 | 2.10 | 11/10 | 47.6% |
| +150 | 2.50 | 3/2 | 40.0% |
| +200 | 3.00 | 2/1 | 33.3% |
| +300 | 4.00 | 3/1 | 25.0% |
| +500 | 6.00 | 5/1 | 16.7% |
| +1000 | 11.00 | 10/1 | 9.1% |
Implied Probability — The Most Useful Concept
Every betting price translates to a percentage chance of winning. That percentage is called implied probability. Once you can read implied probabilities, you immediately see:
- How much edge a sportsbook holds. Sum the implied probabilities for both sides of a wager. The excess over 100% is the vig (margin).
- Whether a bet has positive expected value. If your estimated true win probability exceeds the implied probability, the bet has positive EV.
- How to compare prices across operators. Implied probability normalizes American, decimal, and fractional formats into one comparable number.
Quick Implied Probability Math
- Negative American: implied % = |odds| / (|odds| + 100) × 100. -150 → 150 / 250 = 60%.
- Positive American: implied % = 100 / (odds + 100) × 100. +200 → 100 / 300 = 33.3%.
- Decimal: implied % = 1 / decimal × 100. 2.50 → 1 / 2.50 = 40%.
The Vig (Juice) on -110 Spreads
Most Maryland sportsbook spreads and totals are priced -110 on each side. Implied probability per side is 52.4%. Sum: 104.8%. The 4.8% over 100% is the sportsbook's margin.
To break even on -110 bets, you must win 52.4% of them. Casual bettors typically win 47-49%. To turn a profit, you need to find edges that push your win rate above 53%.
Maryland Bettor Tips for Reading Odds
- Always line shop. Different Maryland sportsbooks post different prices. Even one extra point on a Ravens spread, or +5 on a moneyline, compounds meaningfully over hundreds of bets.
- Watch the vig, not just the line. A "better" line at one book may carry worse pricing (e.g., -120 vs -110). Compute implied probability before deciding which side to take.
- Promo prices distort implied probability. Boosted odds promotions are advertised as +400 or +500 on a multi-leg parlay. Compare the boost against the same parlay\'s "natural" implied probability — sometimes the boost still loses to true odds.
Find the Sharpest Maryland Lines
Some operators consistently post sharper prices on certain markets. Our independent reviews call out where each sportsbook excels.
Odds FAQ
What does -110 mean?
A -110 American moneyline means you must wager $110 to win $100 profit. Decimal equivalent is 1.91. Implied probability is 52.4%. Most spreads and totals are priced -110 on each side.
What does +200 mean?
A +200 American moneyline means a $100 wager wins $200 profit (total return $300). Decimal equivalent is 3.00. Implied probability is 33.3%.
What is implied probability?
Implied probability is the win percentage a price suggests. -110 implies 52.4%; +200 implies 33.3%. Sum the implied probabilities of both sides of a bet — the excess over 100% is the sportsbook's margin (the "vig").
How do I convert American odds to decimal?
For positive American odds: decimal = (American / 100) + 1. For negative: decimal = (100 / |American|) + 1. Example: +200 → 3.00, -150 → 1.67.
Do Maryland sportsbooks use decimal or fractional odds?
All Maryland sportsbooks default to American odds. Most apps offer a settings toggle to display decimal or fractional formats — useful if you came to US betting from Europe or the UK.
What is "vig" or "juice"?
The vig (or juice) is the sportsbook's built-in margin. On a -110/-110 spread, the vig is roughly 4.5%. To break even on -110 bets, you must win 52.4% of them; sharp bettors aim higher.