If you have ever opened a sportsbook app and wondered what the + and - mean in betting, the short answer is simple: a minus sign marks the favorite and tells you how much you need to risk to win $100, while a plus sign marks the underdog and tells you how much you win on a $100 bet.

Those two signs, plus the number next to them, carry everything you need to know about a bet: who the sportsbook expects to win, how much you get paid, and how likely the outcome is according to the price.

This guide walks through how to read American odds step by step, with worked payout examples, the implied probability formula, decimal and fractional conversions, and the common spots where the signs trip up new bettors.

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Betting odds are the price of a bet. They do two jobs at once: they show how likely a sportsbook thinks an outcome is, and they show how much you will be paid if that outcome happens.

U.S. sportsbooks display odds in the American format by default, using a plus or minus sign followed by a number built around a $100 baseline. Most apps also let you switch to decimal or fractional odds in settings, which is covered further down.

The sign in front of the number is the fastest read on any betting board. Here is the one-line version of each:

You do not need to bet $100. The $100 is just the reference point, and every payout scales up or down from there.

Negative odds show the cost of winning $100. The bigger the number after the minus sign, the bigger the favorite and the less you win relative to your stake.

Positive odds show the profit on a $100 bet. The bigger the number after the plus sign, the bigger the underdog and the bigger the potential payout.

You will see -110 more than any other price, especially on point spreads and totals. It means you bet $110 to win $100, or $11 to win $10.

When both sides of a bet are listed at -110, the sportsbook sees the matchup as a coin flip. The extra $10 per $100 is the sportsbook's built-in commission, known as the vig or juice, explained in more detail below.

A typical NFL game in a sportsbook app shows three markets side by side: the point spread, the moneyline and the total. Here is how one game would look:

Read across each row and every plus or minus sign answers a different question. The sections below break down each column.

The moneyline is a straight bet on who wins the game. The Eagles at -180 are favored, so a $180 bet wins $100. The Giants at +150 are the underdog, so a $100 bet wins $150.

For a full walkthrough of this bet type, see our guide on how to bet moneylines.

On the spread, the sign means something different: it shows points, not payout. The Eagles at -3.5 must win by 4 or more for the bet to cash. The Giants at +3.5 cash if they win outright or lose by 3 or fewer.

The number in parentheses, -110 on both sides here, is the price. This is the most common point of confusion for new bettors, so always check whether a minus sign is attached to points or to odds.

The total is a bet on combined points scored by both teams. Over 47.5 wins if the teams combine for 48 or more, and under 47.5 wins at 47 or fewer. Both sides are priced at -110 here. Our over/under betting guide covers totals in more depth.

Baseball and hockey use a fixed spread of 1.5 runs or goals, so the price does more of the work. A favorite on the MLB run line at -1.5 can carry plus odds, like -1.5 (+130), because winning by two or more is far from guaranteed. That is why a plus sign does not always mean underdog, and a minus sign does not always mean favorite, outside of the moneyline.

You can work out any payout with two simple formulas. Profit is what you win on top of your stake, and the total return is profit plus your original bet.

Quick reference for a $100 bet:

Every sportsbook bet slip calculates this automatically before you confirm, so use these formulas to check value rather than to do mental math at the window.

Implied probability turns the odds into the percentage chance the price suggests. It is the single most useful skill for judging whether a bet is worth making.

If you think a team wins more often than its implied probability, the bet has value. If you think it wins less often, the price is too short.

Add up both sides of a -110 and -110 spread, and you get 104.8 percent, not 100. In the Eagles and Giants moneyline above, -180 (64.3 percent) plus +150 (40.0 percent) equals 104.3 percent.

That extra is the vig, the sportsbook's margin. It means you need to win about 52.4 percent of your -110 bets just to break even, which is why comparing prices across sportsbooks matters.

The same price can be shown three ways. American odds are standard in the U.S., decimal odds are common in Europe, Canada and Australia, and fractional odds are traditional in the UK and Ireland, especially for horse racing.

A parlay combines multiple bets into one ticket, and the odds multiply. Two legs at -110 each converts to decimal 1.91 x 1.91, which pays roughly +264. A $10 two-leg parlay at those prices returns about $36.45. Learn more in our parlay betting guide, or see how odds stack within one game in our same-game parlay guide.

Props are priced just like sides and totals. A quarterback over 249.5 passing yards at -115 means you bet $115 to win $100. Our prop betting guide explains how to find value in player markets.

Futures, like Super Bowl or World Series winners, usually carry big plus numbers because so many teams are in the field. A team at +800 pays $80 on a $10 bet and carries an implied probability of 11.1 percent. See our futures betting guide for season-long strategy.

In-game odds update after every play. A pregame +200 underdog that takes an early lead might flip to a minus price within minutes. Read our live betting guide before betting in-game.

Odds are not fixed once posted. Sportsbooks adjust them for two main reasons:

Your price locks in when you place the bet, so a line that moves after you bet does not change your payout. Odds also differ slightly from one sportsbook to the next, which is why serious bettors compare apps. Our best betting apps guide ranks the top options.

The plus and minus logic is the same everywhere, but each sport has quirks worth knowing:

New users can also stretch a first bet with offers like the FanDuel promo code or the DraftKings promo.

Understanding odds helps you know what you are risking, but betting should always stay within a budget you can afford to lose. If gambling stops being fun, free and confidential help is available:

A minus sign marks the favorite and shows how much you need to bet to win $100. A plus sign marks the underdog and shows how much you win on a $100 bet. On point spreads, the sign refers to points instead of payout.

Neither is better by default. Minus odds win more often but pay less, while plus odds pay more but win less often. The better bet is the one where your estimate of the outcome is higher than the implied probability of the price.

It means you bet $110 to win $100, or $11 to win $10. It is the standard price on spreads and totals, and the extra $10 is the sportsbook's vig.

+100 is even money. A $100 bet wins $100 in profit, for a $200 total return, and the implied probability is 50 percent.

You must bet $200 to win $100, or $10 to win $5. The implied probability is 66.7 percent, which makes it a solid favorite.

A $100 bet wins $300 in profit, for a $400 total return. A $10 bet wins $30. The implied probability is 25 percent.

For minus odds, divide the odds by the odds plus 100. For plus odds, divide 100 by the odds plus 100. For example, -150 is 60 percent and +200 is 33.3 percent.

On the moneyline, yes. On spreads, run lines and puck lines, the minus can refer to points, and a favorite giving 1.5 runs or goals can carry plus odds.