Sports Betting Odds Explained
Odds tell you two things: how much you'll win on a successful bet, and how likely the sportsbook thinks the outcome is. Three formats are used worldwide.
American Odds (Used in NJ)
The default at every NJ-licensed sportsbook. American odds are written with a + or - sign followed by a number.
- Negative (-110): Bet $110 to win $100. The favorite. Lower-numbered negatives are bigger favorites.
- Positive (+150): Bet $100 to win $150. The underdog. Higher-numbered positives are bigger underdogs.
The standard NFL spread is priced at -110 on both sides, meaning you risk $110 to win $100 either way. The 5% gap is called the "vig" — the sportsbook's commission.
Decimal Odds (Used in Europe)
Total payout per $1 wagered, including stake. Easy to convert.
- 1.91 decimal = -110 American = bet $1, get back $1.91 if you win
- 2.50 decimal = +150 American = bet $1, get back $2.50 if you win
- 1.50 decimal = -200 American = bet $1, get back $1.50 if you win
Fractional Odds (Used in UK)
Net profit per stake, written as a fraction.
- 10/11 = -110 American = bet $11, win $10 (plus your $11 back)
- 3/2 = +150 American = bet $2, win $3
- 1/2 = -200 American = bet $2, win $1
Implied Probability
Every odds line implies a probability. To convert American odds:
- For negative odds:
|odds| / (|odds| + 100). So -110 = 110/210 = 52.4% - For positive odds:
100 / (odds + 100). So +150 = 100/250 = 40%
The implied probability of both sides of a normal NFL bet adds up to 104.8% (52.4% + 52.4%). The 4.8% extra is the vig — it's why sportsbooks profit long-term.
Quick Conversion Table
| American | Decimal | Fractional | Implied Probability |
|---|---|---|---|
| -300 | 1.33 | 1/3 | 75.0% |
| -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% |
Why Shopping the Line Matters
NJ has 15 licensed sportsbooks and they don't all post the same odds. A typical NFL spread might be -110 at FanDuel, -105 at DraftKings, and -108 at BetMGM. That spread of -105 vs -110 means you risk $105 to win $100 instead of $110 — a 5% difference compounded over hundreds of bets.
For high-volume bettors, having accounts at 3-4 NJ books and always taking the best price is the single biggest +EV move available.
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