Calculator
Half-Point Calculator — What Does Buying a Point Cost?
Most sportsbooks let you "buy" half a point to move a spread in your favor — for a price. Whether it's worth it depends on crossing a key number (like 3 or 7 in the NFL). Enter the original price and the new price after buying the half-point to see the true cost.
Half-point cost in probability percentage tells you how much edge you're giving up. Anything over ~3% is expensive; crossing NFL key numbers (3, 7) may justify up to 4–5%.
Convert the spread to a moneyline →The price before buying the half-point (e.g. -110 at +2.5)
The price the book charges after the move (e.g. -130 at +3)
How this works
Formula
cost = price_at_new_line - price_at_old_line (in cents of American odds)
Worked example
NFL +2.5 -110 → +3 -130: fair cost ≈ 18 cents, book charges 20. Slight -EV to buy.
FAQ
Are key numbers different in each sport?
Yes. NFL: 3 and 7 are by far the most common margins. NBA: smaller spike around even numbers. MLB run line: always 1.5.
Should I ever buy points?
Only when crossing a key number and the book under-prices the half. Books usually over-charge for crossing 3 in the NFL.
What's a teaser?
A teaser is a multi-leg parlay where you buy points on every leg. 6-point NFL teasers crossing 3-and-7 are historically near break-even.
How much should crossing 3 in the NFL cost?
Roughly 25 cents (from -110 to -135). Many books charge 30+. The calculator flags whether you're getting fair price.
Is buying a half-point on totals worth it?
Usually no — totals are smoother than spreads. Half-point moves rarely cross a 'key' total.