Half Point Helper
See what buying half a point on a spread costs and whether it's worth it.
How to Use This Calculator
- Enter the current point spread
- Add the odds at that current spread (in American format, e.g., -110)
- Enter the odds you’d get 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 a bit of extra juice (worse odds) to nudge the spread 0.5 points your way. For instance, shifting from -3 to -2.5 takes away the risk of a push on a game decided by exactly 3 points.
What are key numbers in NFL betting?
Key numbers are the margins of victory that come up most often. In the NFL, 3 is the biggest one (~15% of games), then 7 (~10%), 1 (~6%), and 10 (~5%). Moving across these numbers usually carries the most value.
Is buying a half point usually worthwhile?
It depends on which number you’re crossing. Buying off 3 is nearly always worth it at standard prices, because games land on 3 roughly 15% of the time. Buying off non-key numbers rarely justifies the extra cost.
Does this apply to the NBA too?
NBA margins of victory are spread out more evenly, so no single number carries the weight that 3 does in the NFL. Key NBA numbers are far less pronounced, which makes buying half points generally less worthwhile.