How Do Oddsmakers Set Lines?

Oddsmakers move lines in response to where the public places bets in order to keep an even distribution of money across all markets. See our page on Sportsbook Margins for an explanation of why books want even distribution across markets.

To guarantee a profit, bookmakers need to ensure that the picks coming in for each team in each matchup are as close to 50/50 as possible (if you are unsure why, read up on What are Sportsbook Margins?). But what happens if something suddenly changes? A star player gets injured in training or a big trade happens? What if the bookmaker misread where people were going to put money and set the opening prices incorrectly?

Money will start coming in more on one side than the other and the oddsmaker becomes “exposed”. There is the potential for the oddsmaker to have to payout more than they took on the event if the side with the most action wins!

To help avert disaster scenarios like this, oddsmakers are constantly monitoring the picks that are coming in to ensure that they are as close to 50/50 as possible in order to preserve their profit margin.

There are two ways that oddsmakers can make one side more attractive than the other, moving the action back to 50% per side:

1. Move the lines:

Say the line is set at +7.5 for the underdog, -7.5 for the favourite, but too much money is coming in for the underdog. That means that +7.5 is too many points for the underdog and more than half the money is coming in on that side. To balance the action an oddsmaker will reduce the amount of points given to the underdog to +7 or +6.5, increasing the amount that the public bets on the favourite and reducing what they bet on the underdog.

2. Change the prices:

If it is a moneyline market, or only a slight adjustment needs to be made to a total or spread market, the oddsmaker will change the price for a side. You will commonly see a total or spread market with slightly different prices per side, for example:

Over 45.5 – 1.87
Under 45.5 – 1.98

This brings in more action on the under, without oddsmakers having to give bettors an entire half point.

Many people have a misconception that every oddsmaker out there competes with each other based on having the best odds. In reality, that’s not completely true. An oddsmaker’s first priority above all else is keeping the picks as near to 50/50 as possible, otherwise they wouldn’t stay in business very long at all. This means that prices can vary between books, based on the preferences of the users at that book.

It pays to shop around and compare odds. You might be risking far too much unnecessarily. Take the time to find the oddsmakers with the best odds, and then invest the time in the process to open an account with them. Your sportsbook balance will thank you for it later.