If you have ever looked at a betting line and seen numbers like -7.5, -110 or +170 and wondered what they actually mean, you are not alone. Mobile sports betting has been live in New York since January 2022, and the state comptroller’s latest report shows more than $91 billion has been wagered since launch. Plenty of those bets are placed without anyone translating the numbers into probabilities. A few minutes of arithmetic changes that.
What a moneyline tells you
A moneyline is a bet on who wins, with no points involved. American odds show it in two ways:
- A minus sign marks the favorite and shows how much you must stake to win $100. At -200, you bet $200 to win $100.
- A plus sign marks the underdog and shows your profit on a $100 stake. At +170, a $100 bet wins $170.
Every price implies a probability. For a negative line, divide the number by itself plus 100. For a positive line, divide 100 by the number plus 100.
- -200 implies 200 / 300 = 66.7%
- +170 implies 100 / 270 = 37.0%
Why the two sides add up to more than 100%
Add those figures together and you get 103.7%, not 100%. The extra 3.7% is the sportsbook’s margin, built into the price. Remove it and the fair chances are about 64.3% for the favorite and 35.7% for the underdog. Sportsbooks earn their income from that gap, which is why odds never mirror the true likelihood exactly.
Point spreads and the famous -110
A point spread levels the game by giving the underdog a head start. If a team is -7.5, it must win by eight or more for a bet on it to pay. A bet on the other side wins if that team loses by seven or fewer, or wins outright.
Most spreads are priced at -110 on both sides. That means you risk $110 to win $100. The price implies a 52.38% chance (110 / 210), and two sides at 52.38% add up to 104.76%. That extra 4.76% is the “vig,” or “juice.”
What the vig costs over time
The important number is the break-even point. At -110, you have to win 52.38% of your bets just to come out even. Win exactly half and you lose money:
- 100 bets of $110 means $11,000 staked.
- 50 wins pay $100 each, so +$5,000.
- 50 losses cost $110 each, so -$5,500.
- Net result: -$500, about 4.5% of everything you staked.
That is the real cost of betting even a perfectly balanced slate of games. It also explains why sportsbooks can quote near-even prices on both sides and still profit.
Do the math before you place the bet
You don’t need to memorize formulas. A free odds calculator converts any format (American, decimal, fractional or percentage), then shows the payout, the profit and the implied chance. Try it on the lines you are looking at this weekend, and it quickly becomes clear how much of each price is margin. Margins also differ from one sportsbook to the next, so it is worth comparing sports betting sites on price before you settle on one.
Habits that keep betting in perspective
- Know the break-even point. At -110, it is 52.38%. Ask yourself whether you really expect to clear it.
- Compare prices across licensed apps. A half-point on a spread or a few cents on a moneyline can add up over a season.
- Be wary of long parlays. Each leg carries its own margin, so the cost grows with every game added.
- Set a budget before kickoff and treat it as entertainment spending.
- Never chase losses. A bad Sunday doesn’t change the odds on Monday night.
Mobile sports betting in New York is limited to people 21 and older who are physically in the state, and licensed apps are the only legal option. If betting stops being fun, free and confidential help is available 24/7 through the New York State HOPEline at 1-877-8-HOPENY (467369), or by texting HOPENY (467369).
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