Half Point Sports Calculator
See what buying half a point costs and if it's worth it.
How to Use This Calculator
- Enter the current point spread
- Enter the odds at the current spread (in American format, e.g., -110)
- Enter the odds if you buy a half point (e.g., -120)
- See the cost in implied probability and whether buying the half point is worth it
Formula
Implied Probability from American Odds:
- Negative: |Odds| / (|Odds| + 100) x 100
- Positive: 100 / (Odds + 100) x 100
Cost of Half Point = Implied Prob (Half Point Odds) - Implied Prob (Current Odds)
Worth buying if Cost < Probability of game landing on the number
Frequently Asked Questions
What does buying a half point mean?
Buying a half point means paying extra juice (worse odds) to nudge the spread by 0.5 points in your favor. For instance, going from -3 to -2.5 wipes out the chance of a push on exactly 3 points.
What are key numbers in NFL betting?
Key numbers are the most common margins of victory. In the NFL, 3 is the biggest one (~15% of games), then 7 (~10%), 1 (~6%), and 10 (~5%). Moving off these numbers usually gives you the most value.
Is buying a half point normally worth it?
It comes down to the number. Buying off 3 is nearly always worth it at standard prices, since games land on 3 about 15% of the time. Buying off non-key numbers rarely justifies the extra cost.
Does this apply to the NBA too?
NBA winning margins are spread out more evenly, so no single number carries the weight that 3 does in the NFL. Key NBA numbers are less sharp, which makes half-point purchases generally less worthwhile.