Definition
Buying points means paying extra juice to move a spread or total to a better number. On a spread bet, that can turn −3.5 into −3, or +2.5 into +3. On a total, it can move over 45.5 to over 44.5.
The math is the price change. Break-even probability is:
risk / (risk + win)
At −110, risking $110 to win $100 requires:
110 / (110 + 100) = 52.38%
At −130, risking $130 to win $100 requires:
130 / (130 + 100) = 56.52%
Worked Example
An NFL favorite is listed at −3.5 odds of −110. A sportsbook offers −3 at −130.
If you bet −3.5 at −110, you risk $110 to win $100 and need to win 52.38% of bets to break even.
If you buy to −3 at −130, you risk $130 to win $100 and need to win 56.52% of bets to break even.
The bought point helps only when the game lands exactly on 3. A −3.5 ticket loses by one point; a −3 ticket pushes.
Why It Matters
Buying points helps when the moved number crosses a key scoring margin, such as 3 or 7 in football. The added push or win value must be worth more than the higher break-even price.