American odds, also called moneyline odds, express a price as a number with a plus or minus sign, anchored to a one hundred dollar reference stake.
Last reviewed 9 November 2025 · Educational, not advice
American odds, often called moneyline odds, are the plus and minus format used widely in the United States to quote a price on an outcome. Every quote is a whole number with a sign, and both are anchored to a reference figure of one hundred dollars. The sign tells you which side of that reference you are on, and the size of the number tells you how long or short the odds are. The format looks unusual at first, but it reduces to two simple rules.
A negative number marks the favored side. It tells you how much you would need to stake to make one hundred dollars of profit. Minus one hundred fifty means you would stake one hundred and fifty to win one hundred. A positive number marks the less favored side. It tells you the profit a one hundred dollar stake would return. Plus one hundred fifty means a one hundred dollar stake would win one hundred and fifty. The further the number sits from zero, the longer the odds, so plus four hundred is a bigger longshot than plus one hundred twenty, and minus five hundred is a stronger favorite than minus one hundred ten.
The most useful thing you can do with American odds is turn them into an implied probability, because that is what lets you compare them with a prediction market price. For negative odds, take the number without its sign, and divide it by that same number plus one hundred. Minus one hundred fifty becomes one hundred fifty divided by two hundred fifty, which is sixty percent. For positive odds, divide one hundred by the odds plus one hundred. Plus one hundred fifty becomes one hundred divided by two hundred fifty, which is forty percent. Even money, the point where a stake doubles, is plus one hundred or minus one hundred, an implied fifty percent.
There is a catch worth understanding. Add up the implied probabilities a sportsbook quotes on all sides of an event and the total comes to more than one hundred percent. That extra is the built in margin, sometimes called the vig or the overround, and it is how the book makes money regardless of the result. So the implied probability you read off a single set of odds is slightly inflated, and the true probability the book assigns is a little lower once the margin is stripped out.
This is where the contrast with a prediction market becomes clear. A prediction market price in cents already reads as a percentage, so a contract at sixty cents is an implied sixty percent, no conversion needed. In an exchange model the price comes from participants trading rather than a book setting a margin, though fees still apply. Knowing how to move between American odds and a market price lets you see the same chance expressed two ways. It does not tell you which way an event will go, and we never name a predicted result.
An outcome is quoted at minus two hundred. Stripping the sign, two hundred divided by three hundred is about sixty seven percent implied. The other side is quoted at plus one hundred seventy, so one hundred divided by two hundred seventy is about thirty seven percent. The two add to roughly one hundred and four percent, and that four percent over one hundred is the margin. On a prediction market the same outcomes might show near sixty five cents and thirty five cents, a probability read without conversion.
Illustrative only. Numbers are examples, not a quote or a prediction, and exclude fees.
Odds describe a price and an implied chance, not a prediction of the result, and quoted odds usually carry a margin. Prediction markets can lose you money. Stake only what you can afford to lose, never to chase a loss, and never on borrowed money. In the United States you can call or text the helpline on 1-800-GAMBLER or visit ncpgambling.org.
American odds, also called moneyline odds, express a price as a number with a plus or minus sign. A positive number shows the profit on a one hundred dollar stake, and a negative number shows the stake needed to make one hundred dollars of profit.
Minus odds mark the favored side and tell you how much you must stake to win one hundred. Plus odds mark the less favored side and tell you the profit a one hundred dollar stake would return. The further a number is from zero, the longer the odds it implies.
For negative odds, divide the number, ignoring the sign, by that number plus one hundred. For positive odds, divide one hundred by the odds plus one hundred. So minus one hundred fifty implies about sixty percent and plus one hundred fifty implies about forty percent, before any margin.
Both encode an implied probability. A prediction market price in cents reads directly as a percentage, while American odds need a small conversion. Comparing them lets you see the same chance expressed two ways, though sportsbook odds usually include a built in margin.
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