NBA Over/Under Betting — How Totals Work and How to Find Value
The over/under — also called the total — is the NBA betting market that has nothing to do with who wins. You're simply predicting how many points will be scored in the game combined.
How it works
The bookmaker sets a total for each game. Say the total for Boston vs Philadelphia is set at 218.5. You bet on whether the combined final score will be over or under that number.
If Boston win 112-109, the combined total is 221. Over wins. If Boston win 108-104, the combined total is 212. Under wins.
That's it. The result doesn't matter. One team could blow the other out and your over/under bet is completely unaffected by the margin of victory.
Both sides — over and under — are typically priced at around 1.91.
What affects NBA scoring?
This is where it gets interesting. Several factors push games towards higher or lower totals:
Pace of play. Some teams play fast — lots of possessions, lots of shots. Others slow it down. When two fast teams play, totals go up. When two slow teams play, totals come down. Pace data is public and easy to find.
Offensive and defensive ratings. A team's offensive rating measures how many points they score per 100 possessions. Defensive rating measures how many they allow. When a high-powered offence plays a weak defence, the total is naturally higher.
Rest and fatigue. Teams on the second night of a back-to-back often score fewer points and defend worse due to fatigue. This can push totals either way depending on which team is tired.
Playoff vs regular season. Playoff basketball is significantly lower scoring than the regular season. Defences are more organised, rotations are shorter, and teams have had time to prepare specific game plans. If you're using regular season averages to project playoff totals, you'll consistently be too high.
Home court. Home teams tend to score slightly more than away teams due to crowd energy and familiarity with the court.
How does the model project totals?
The HMJOROTips NBA model projects a score for each team based on their offensive and defensive ratings — how much each team scores when they play teams of similar quality. The projected scores are added together to get the projected total.
If the model projects a combined total of 224 and the bookmaker has the line at 216.5, the model says over. If the projection is 212 and the line is 218.5, the model says under.
The edge is in the gap between the model's projection and the bookmaker's line. The bigger the gap, the more confident the pick.
Totals in the playoffs
One important adjustment — the NBA model accounts for the fact that playoff games are lower scoring. The bookmaker's line already reflects this to some extent, but projection models built on regular season data need to be recalibrated for the postseason.
During the playoffs, focus on games where teams are playing each other for the third or fourth time in a series. By that point both coaches have adapted their defensive schemes and scoring tends to be even lower than early in the series.
