How to read betting odds: American, decimal and fractional
By Sharp Signal Labs ·
Betting odds do two jobs at once. They tell you how much a winning bet pays and, read the right way, how likely the market thinks the outcome is. The same price can be written three ways: American odds (used in the US), decimal odds (Europe, Canada, Australia and much of Asia) and fractional odds (the UK and Ireland). This guide walks through all three, then the main bet types and the built-in cost called the vig.
American odds: the minus and the plus
American odds, also called moneyline odds, are built around $100.
- A minus number marks the favorite and shows how much you must risk to win $100. At -110 you risk $110 to win $100; a winning bet returns $210, your stake included.
- A plus number marks the underdog and shows what a $100 bet wins. At +150, $100 wins $150 and returns $250.
- +100 (or -100) is even money: risk $100 to win $100.
So what does -110 mean? It is the standard price on US spreads and totals: risk $110 to win $100. In decimal odds it is 1.91, and it implies a 52.4% chance.
Decimal odds: the total return
Decimal odds show the total return for every 1 unit staked, stake included. At 1.91, a $10 bet returns $19.10 — $9.10 of winnings plus the stake. At 2.50, $10 returns $25. Winnings are always stake × (decimal − 1), which makes decimal the easiest format for math.
Fractional odds: winnings over stake
Fractional odds show winnings relative to stake. 5/2 means you win 5 for every 2 staked, so $10 wins $25 and returns $35. 10/11 means you win 10 for every 11 — the same price as -110. “Evens” (Evs) is 1/1, the same as +100 or 2.00. When the first number is smaller than the second, as in 1/2, the selection is “odds-on”: a favorite.
Implied probability
Every price implies a chance of winning:
- Decimal: 1 ÷ odds. 1.91 → 52.4%.
- American minus: odds ÷ (odds + 100), using the number without its sign. -110 → 110 ÷ 210 = 52.4%.
- American plus: 100 ÷ (odds + 100). +150 → 100 ÷ 250 = 40.0%.
- Fractional a/b: b ÷ (a + b). 10/11 → 11 ÷ 21 = 52.4%.
These are the bookmaker's numbers with the margin included, so the sides of one market add up to a little more than 100%.
Odds conversion table
| American | Decimal | Fractional | Implied probability |
|---|---|---|---|
| -200 | 1.50 | 1/2 | 66.7% |
| -150 | 1.67 | 4/6 | 60.0% |
| -110 | 1.91 | 10/11 | 52.4% |
| +100 | 2.00 | Evs | 50.0% |
| +150 | 2.50 | 6/4 | 40.0% |
| +200 | 3.00 | 2/1 | 33.3% |
| +300 | 4.00 | 3/1 | 25.0% |
| +500 | 6.00 | 5/1 | 16.7% |
Fractional prices are the standard UK quotes — 6/4 is the same as 3/2. For any other price, use the odds calculator.
Moneyline, spread and total
Moneyline: pick the winner. The favorite carries a minus price and the underdog a plus price, for example -150 / +130. In soccer the moneyline has three outcomes, called 1X2: 1 is a home win, X a draw and 2 an away win.
Spread: the favorite gives points and the underdog gets them. Team A -3.5 (-110) has to win by 4 or more; Team B +3.5 (-110) covers by winning or by losing by 3 or fewer. Baseball calls it the run line and hockey the puck line, both usually set at 1.5. Soccer's version is the Asian handicap, quoted in half and quarter goals, which takes the draw out of the bet: at -0.5 the team has to win; at 0 a draw refunds your stake; a quarter line such as -0.75 splits your stake between -0.5 and -1, so a one-goal win pays out on half and refunds the other half.
Total (over/under): bet on the combined score finishing over or under a number — 44.5 points in the NFL, 8.5 runs in MLB, 2.5 goals in soccer. A half-point total can't push; when the score lands exactly on a whole-number total, the bet is a push and your stake comes back. Soccer quarter totals such as 2.75 split the stake the same way as Asian handicaps.
The vig: what a -110 price costs
The bookmaker's cut is built into the price. It is called the vig, vigorish or juice. On a spread priced -110 on both sides, each side implies 52.4%, so the pair adds up to 104.8% instead of 100%. That total is the overround, and the extra 4.8 points are the margin built into the prices. Measured against the money bet, the cut is about 4.5%: if $110 is bet on each side, the book takes in $220, pays the winner $210 and keeps $10.
Two things follow. At -110 you need to win 52.4% of your bets just to break even. And the fair, no-vig price of a true 50/50 is 2.00, or +100. The no-vig calculator strips the margin from any market.
Putting it together
In the SharpPick app you choose how odds are shown — American, decimal or fractional — and every price follows your choice. To see how prices change before a game, read what line movement is or check today's dropping odds.