Every recreational bettor placing serious money on sports needs to understand vig — the bookmaker's edge — before they will be able to win in the long run. This guide is the practical primer: how American odds work, how to convert them to implied probability and decimal odds, what -110 actually means, and why hold percentage matters more than any specific wager outcome.
American Odds — The Default Format in NY
Every licensed New York sportsbook displays odds in American format by default. American odds are denominated relative to $100 of wager:
- Negative odds (-110, -150, -200): How much you need to bet to win $100
- Positive odds (+150, +200, +500): How much you win for every $100 bet
Examples:
- Bills -7 at -110: Bet $110 to win $100 (total return $210 if you win)
- Yankees ML at -200: Bet $200 to win $100 (total return $300 if you win)
- Knicks ML at +150: Bet $100 to win $150 (total return $250 if you win)
- Underdog player prop at +500: Bet $100 to win $500 (total return $600 if you win)
Converting American to Decimal Odds
Decimal odds are the European/Asian convention. They show total return per $1 wagered.
- Negative American: Decimal = (100 / |American odds|) + 1. So -110 = (100/110) + 1 = 1.91
- Positive American: Decimal = (American odds / 100) + 1. So +150 = (150/100) + 1 = 2.50
Decimal odds make some calculations easier (parlay multiplications especially), but every licensed NY sportsbook will default to American. You can usually toggle the display in app settings.
Implied Probability — The Critical Number
Implied probability is the percentage chance the bookmaker is saying an outcome will occur. It is the most important concept in sports betting.
- Negative American: Implied % = |American odds| / (|American odds| + 100). So -110 implies 110/(110+100) = 52.4% probability.
- Positive American: Implied % = 100 / (American odds + 100). So +150 implies 100/(150+100) = 40.0% probability.
Quick reference table:
| American Odds | Decimal Odds | Implied Probability |
|---|---|---|
| -300 | 1.33 | 75.0% |
| -200 | 1.50 | 66.7% |
| -150 | 1.67 | 60.0% |
| -110 (standard vig) | 1.91 | 52.4% |
| +100 (even money) | 2.00 | 50.0% |
| +110 | 2.10 | 47.6% |
| +150 | 2.50 | 40.0% |
| +200 | 3.00 | 33.3% |
| +500 | 6.00 | 16.7% |
For doing this on your phone in real time, our betting tools page has a free American-to-decimal-to-implied converter.
What "-110" Actually Means — The Vig
The standard NFL spread line is -110/-110. Both sides offered at -110. Both sides implied probability of 52.4%. That sums to 104.8% probability — more than 100%. The "extra" 4.8% is the vigorish, or vig.
The vig is the bookmaker's edge. It's the price you pay to make the wager. For a single -110/-110 wager:
- Bet $110 to win $100, or bet on the other side, $110 to win $100
- If the true probability is exactly 50/50, you win $100 half the time and lose $110 half the time
- Expected value per $110 wagered: 0.5 * $100 - 0.5 * $110 = -$5
- That's a -4.55% expected return on every dollar wagered
To break even on -110 wagers, you need to win 52.4% of your wagers. To profit, you need to win more than 52.4%. This is mathematically why most recreational bettors lose — not because they're picking badly, but because they're paying 4.55% in vig on every wager and the typical recreational win rate is around 49-51%.
Hold Percentage — The Honest Measure of a Sportsbook
"Hold" is the operator's gross gaming margin as a percentage of handle. It reflects how much of the bettor's wagers the operator keeps after paying out winners. NY sports betting operators report hold quarterly:
- Industry-low hold (good for bettors): 4.5-5.0% — implies tight markets, sharp lines
- Industry-median hold: 7-9%
- High hold (bad for bettors): 10%+ — implies wide markets, soft lines, less competitive pricing
FanDuel, DraftKings, and BetMGM all report hold percentages in the 8-9% range. The offshore brands we recommend operate at 4.5-6% hold on most markets. Lower hold = more value for bettors. Always.
How Vig Compounds
Place 100 wagers of $100 each at -110/-110, with a true 50/50 outcome distribution:
- Total wagered: $11,000
- Total won: 50 wins × $100 = $5,000
- Total lost: 50 losses × $110 = -$5,500
- Net: -$500
You lose 4.55% of your total wagered amount over the long run, exactly equal to the vig. This is why beating sports betting is hard. You're not just trying to predict outcomes; you're trying to predict outcomes well enough to overcome the structural -4.55% expected value drag on every wager.
Practical Implications
- Line shop. If you can find -107 on the same wager that's -110 elsewhere, you've reduced vig from 4.55% to 3.3%. Over a year of wagering, that's the difference between mid-single-digit losses and breaking even.
- Avoid high-hold markets. Player props typically hold 8-12%. Parlay odds compound vig across legs. Live betting holds 5-8% on average, sometimes higher.
- Use no-vig fair pricing as your reference. If FanDuel offers Bills -3 at -110/-110, the no-vig fair line implies 52.4% / 47.6% (over /under). If you think Bills cover at 55%, you have +EV at the no-vig price. Your edge has to exceed the vig for the wager to be profitable.
- Track your own win rate by market. If you're a 48% bettor on NBA spreads but a 53% bettor on MLB totals, the math says to concentrate wagering on the markets where you actually have edge.
For the full Kelly criterion sizing of bets given your win rate, see our Kelly & bankroll management guide. For free betting tools that handle these conversions, see our betting tools page.
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