How to Read American Odds
American odds are built around $100. Once you internalize that single idea, every spread, moneyline, and total becomes readable in seconds.
Every number you see on a US sportsbook board is anchored to a $100 reference. A minus sign tells you how much you'd risk to win $100; a plus sign tells you how much you'd win on a $100 bet. That's the whole system.
The two flavors: minus and plus
A favorite is listed with a minus, like -200. That means you risk $200 to win $100 in profit — a total return of $300 if it hits. An underdog is listed with a plus, like +150. There you risk $100 to win $150 in profit, for a $250 total return.
Notice the asymmetry: the favorite requires more risk for less profit, the underdog offers more profit for less risk. The odds are just a price tag on each side's probability.
Underdog +150 → risk $100 to profit $150
Payout on a $50 bet at -200:
Profit = (50 / 200) × 100 = $25.00
Converting odds to a payout
For a minus number, profit = (stake / odds) × 100. For a plus number, profit = (stake / 100) × odds. The full payout adds your original stake back on top. A $110 bet at -110 returns (110/110)×100 = $100 profit plus your $110 stake, for $210 total — which is why the standard point spread at -110 pays roughly 91 cents on the dollar.
Why the -110 spread is the workhorse
Most point spreads and totals are priced at -110 on each side. That means a bettor who wins exactly half their wagers at -110 still loses money — a $110 bet returns $210, so 50/50 over many bets produces a slow bleed. This gap is the vig, the commission baked into the price. Understanding it is the difference between betting for fun and betting with an edge.
When to switch to decimal
American odds are great for reading payouts, but they're clumsy for math. If you want to compare prices, compute implied probability, or shop lines across books, convert to decimal first: divide a minus number into 100 and add 1, or divide a plus number by 100 and add 1. Decimal odds of 1.91 mean a $100 bet returns $191 total — equivalent to -110.
Decimal = (150 / 100) + 1 = 2.50 (for +150)
Reading the board at a glance
On a typical NFL board, the spread (e.g., -3.5) sits next to its price (-110), the moneyline is listed outright, and the total has an over and under each priced separately. The spread tells you the expected margin; the moneyline tells you the outright win price; the total tells you the expected combined score. Each market prices a slightly different question.
Key takeaway: American odds are always relative to $100 — minus is what you risk to win $100, plus is what you win on $100. Master payouts on paper first, then graduate to implied probability to start finding value.