Half Point Calculator
Price the cost and value of buying half points on a spread against the added juice.
How to Use This Calculator
- Input the current point spread
- Input the odds at the current spread (American format, e.g., -110)
- Input the odds if you buy a half point (e.g., -120)
- The tool returns the cost in implied probability and whether buying the half point is justified
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 is meant by buying a half point?
Buying a half point means accepting extra juice (worse odds) in exchange for shifting the spread 0.5 points in your favor. For instance, moving from -3 to -2.5 removes the push risk on an exact 3-point result.
Which are the key numbers in NFL betting?
Key numbers are the most frequent margins of victory. In the NFL, 3 dominates (~15% of games), trailed by 7 (~10%), 1 (~6%), and 10 (~5%). Crossing these numbers tends to carry more value.
Is buying a half point generally worthwhile?
It comes down to the number. Buying off 3 is nearly always worth it at standard pricing, since games settle on 3 roughly 15% of the time. Buying off non-key numbers rarely justifies the added cost.
Does this apply to NBA?
NBA victory margins 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 half-point purchases generally less valuable.