First-half bets work in the same manner as traditional flat bets, but are only concerned with the score at halftime, which is when the bet will be graded as a win or a loss. If, for example, the Chicago Bears are favored by 6 points with a total of 46, a first-half line will likely see the Bears favored by 3-4 points, with a first half total of 23 or 23.5. The first-half line does not simply divide the full game line in half. A 35-point favorite in college football will often be closer to a 21-point favorite in the first half, as the favorite is expected to play better in the first half on the assumption that it will pull its starters at some point in the second half.
Conversely, in college basketball games, it’s expected that roughly 10 more points will be scored in the second half than the first. If the total for the full game is 140, a first-half total would likely be between 65 and 66 points.
The equivalent of a first-half bet for baseball is a five-inning bet, which is becoming more popular as the number of poor relief pitchers appears to be at an all-time high. Bettors are finding they can essentially remove the bullpen from the equation by betting the first five innings. The prices on underdogs are frequently smaller on five-inning bets, while totals are typically close to one-half of the full-game total.
A halftime bet is closely related to a first-half bet, but now we’re only concerned with the score of the second half of the game. As the name implies, halftime bets are wagers made at halftime of a game and are available for nearly all NBA and NFL games, along with many of the major college games. When a game reaches halftime, the sportsbooks will post odds for the second half, so you have a small time frame to place your bet before the second half begins. Halftime odds are posted both on the side and the total.
The biggest influence on the halftime line is obviously the score of the game. The halftime odds are going to be different if a 14-point favorite trails 24-10 at halftime than they will be if the favorite leads 24-10 at the half.
If a college football team leads another 38-0 at halftime the second-half total may only be 21, as both teams will likely be trying to run out the clock and have many of their backups in the game. While some halftime odds may look too good to be true, the sportsbooks aren’t dummies and use computer models to help them set the halftime lines, as they only have a minute or two to create the lines and give bettors the opportunity to wager on them before the game resumes.