NFL key numbers

The numbers

• 3 is the most common final margin by a distance: one field goal.
• 7 is the next most common: one touchdown and the extra point.
• 10, 6, 4 and 14 come up often enough to matter, well behind 3 and 7.

Most other margins are much rarer. A game landing exactly on 5, 8 or 9 happens, but nothing like as often as 3 or 7.

Why half points matter

A spread of −3 pushes when the favorite wins by exactly 3. Move it to −2.5 and those games win; move it to −3.5 and they lose. Because so many games land on 3, that half point is worth far more than a half point between, say, 4.5 and 5.5.

• Crossing 3 or 7 changes a bet's chance much more than crossing any other number.
• Books charge for it: buying a favorite down from −3 to −2.5 costs much more in price than buying a half point anywhere else.
• When the market moves a line off 3, the move means more than its size suggests. When it moves from 3.5 to 4.5, it means less.

Using them

• Line shopping: getting +3 instead of +2.5, or −2.5 instead of −3, is worth paying a little extra vig for.
• Line movement: a move onto or through 3 or 7 is a big move. A move that stays between key numbers is a small one.
• Teasers: a teaser moves the lines on several legs in your favor for a lower payout. The classic use is moving a line through both 3 and 7, such as an underdog from +1.5 up to +7.5, or a favorite from −7.5 down to −1.5. A teaser is still a parlay, and the vig still compounds.
• Totals have key numbers too, from common score combinations, but they are much softer than the spread's.