On this page: What Are Betting Lines? The Main Types Of Sports Bets How Odds Work Converting Odds Determining Odds Changing Odds FAQs What are betting lines?Betting lines are displays of the odds for the different main bets you can place. They show the given odds for a number of main bets and are easy enough to understand once you know how the main types of bet work. The way they’re displayed can vary. Football betting lines may look different from hockey betting lines, for example. Once you’re familiar with how they work, you should be able to work them out for yourself easily enough.The main types Of sports betsSports bets can be grouped into four different categories. Below you’ll find a summary of each of these categories. Three of them focus on the result of a match, while the other type covers pretty much everything else about a match or event that can be bet on.Moneyline betsThese are pretty much the simplest type of sports bet you’ll come across. If you place a moneyline bet, you’re backing a team to win. If your chosen team wins the match, you’ll receive a payout and will have your bet returned to you.If, on the other hand, your team loses, you’ll lose your bet and won’t receive an additional payout. A team that’s more likely to win will have lower odds and a smaller payout. For a team that’s regarded as the underdog, the odds are higher and the payouts higher too. Moneyline bets are also known as win bets.Spread betsFor these bets, the team that’s generally seen as most likely to win is given a handicap to give the lesser team an advantage. The purpose of these bets is to making betting on the underdog more attractive.Bookies assign a positive or negative number to each team. The favourite is usually given a negative number and the underdog a positive number. For the favourite to win, they have to not only win the match but also earn enough spread points to beat the underdog.If the favourite is given -3 and the underdog +1, for example, the favourite would need to win four points more than the underdog to draw and five more points to beat the underdog.Over/under betsAlso known as point total bets, these are bets that focus on the final number of goals scored or points earned in a match. The bookie will come up with a number for a particular match. You choose to place either an under bet or an overbet.If the match’s score is greater than this, over bets win; likewise, if the match’s score is less than this, under bets win. If the bookie correctly predicts the final score, all bets are returned.Proposition betsThese are basically any bets that don’t fall under the three categories mentioned above. They cover statistics and events that happen during a match that don’t affect the final outcome. Examples include a particular player scoring a number of times, which team scores first and players being substituted.How odds workOdds represent how much money you’ll stand to win in comparison to your bet, should your bet go on to win. There are three main ways in which these are represented. There’s the European format (decimal odds), the American format (moneyline odds) and the UK format (fractional odds).Let’s start with the UK format. At UK bookies and online sportsbooks, odds are represented as a fraction, i.e. 2/1 – this is pronounced ‘two to one’. The number on the right refers to your wager and the number on the left refers to how much money you stand to win in relation to your wager. If you place a £10 wager with odds of 2/1 and you win, you’ll receive your £10 back, as well as an additional £20 payment. If the number on the left is bigger, your extra payout will be bigger than your original bet. If the number on the left is smaller, your payout will be smaller than your bet. Let’s say you win a 4/5 bet that you placed £5 on. You’d receive your £5 back as well as £4. To calculate how much you could win, divide your bet by the number on the right then multiply it by the number on the left.For European or decimal odds, a decimal number is used, e.g. 2.00. The number represents the total winning amount you stand to receive, including your original bet. If you place a £10 wager and the odds are 2.00, the total amount you’ll receive should you win is £20 – bear in mind this includes your initial £10 wager.For American or moneyline odds, a large positive or negative whole number is used. If it is a positive number, this refers to how much money you stand to win for a $100 bet, in addition to your stake. If you place a $100 wager and the odds are given as +200, this means that if you win, you’ll be paid $200, along with having your wager returned to you. If the odds are negative, this refers to how much you have to wager to win $100.Converting oddsAgain, most of the time when betting on sports and other events in the UK, fractional odds will be used. Many sites will let you switch between different odds formats. Below you’ll find a guide to converting odds between formats:UK to European (fractional to decimal)Take the left-hand number and divide it by the right-hand number, then add one. 1/3 would become 1.33.UK to American (fractional to moneyline)If the number on the left is bigger, times that number by 100 and stick a plus sign in front of it. For example, odds of 9/1 would be +900. If the number on the right is bigger, times it by 100 but add a minus sign in front of it. For example, odds of 1/9 would be -900.European to UK (decimal to fractional)Take away 1 and then convert the number into the lowest possible fraction. For odds of 4.00, you would take away 1 to be left with 3.00. Converted into a fraction, this would be 3/1.European to American (decimal to moneyline)If the odds are 2.00 or greater, you simply take away 1 and times by 100 and add a plus sign. Odds of 3.00 would, therefore, be +200. For odds of less than 2.00, take away 1 and then do minus hundred divided by this number. Odds of 1.25 would be -400.American to UK (moneyline to fractional)If the odds are positive, divide the number by 100 and convert into the simplest fraction. For example, odds of 300 would become 3/1. For negative odds, do 100 divided by the odds (taking away the minus sign) and then reduce to the simplest fraction. So for odds of -400, it would be 1/4.American to European (moneyline to decimal)If the odds are positive, divide the sum by 100 and add 1. Odds of +300 would, therefore, be 4. For negative odds, take away the minus sign and divide 100 by this number. Then, just add 1. If you start off with odds of -400, this would become 1.25.Determining the oddsThe odds for any given match or event can clearly vary quite a lot between online sportsbooks and the more traditional bricks-and-mortar bookies. This is usually because bookies have a lot more independence to set their own odds. When determining the odds, their primary aim is to make a profit, no matter what the bet is.This is understandable, after all, since bookies are businesses that need to keep generating income. A lot of time and research go into determining the actual chances of matches or events resulting in a particular outcome. When it comes to setting the odds, bookies will more often than not adjust them slightly so they stand to make money.Changing the oddsIt is quite common for odds to change. Once a bet has been made available, there is a good chance the odds will be adjusted before the bet is settled. If a lot of punters place significant sums of money backing a particular team, the odds may be adjusted so that the bookie doesn’t end up losing too much money.Other things such as a player getting injured, the weather on the day or changes to a team’s line-up, personal issues or even just the bookies themselves deciding to play it safe.Bear in mind that if you place a bet and the odds change after you’ve placed the bet, your original odds still stand.So let us say you place a £10 wager on Team A winning at odds of 3/5. Closer to the match, the odds for Team A have changed to 2/5. Team A goes on to win. You would get paid at odds of 3/5 since these were the odds when you placed your bet, and not at the later odds of 2/5.So if the odds can change, when should you place your bets? There is no hard and fast rule as to when the best time to get your bets placed is. If you come across odds that are really good, there is always a chance they’ll worsen, so you might want to place your bets then and there. If you’re going to bet on something at the last minute, you may want to consider betting on the underdog. Many punters will go for the favourite right before the match starts, so you may stand to win a decent payout should the underdog go on to win.