Key numbers in football

Football scores come in chunks of 3 and 7. That means final margins are not spread evenly. They pile up on a handful of numbers, and those numbers change how much a half point is worth.

The key numbers

In the NFL, the most common final margins are 3, 7, 6, 10, 14 and 4. Roughly one NFL game in 7 lands on exactly 3. About one in 10 lands on 7.

College football is spread out more, because the talent gaps are wider and scores run higher. The key numbers there are 3, 7, 10, 14, 4 and 17, and each one carries less weight than in the NFL.

Margin	NFL, rough share of games	NCAAF, rough share of games
3	14% to 15%	8% to 9%
7	9% to 10%	6% to 7%
6	6% to 7%	3% to 4%
10	5% to 6%	4% to 5%
14	4% to 5%	4% to 5%
4	4% to 5%	3% to 4%
17	2% to 3%	3% to 4%

These are approximate ranges. They shift a little by era. The NFL extra point change in 2015 and the two-point attempt rate have both nudged the numbers over time.

Why a half point on 3 or 7 matters more

A half point only matters when the game lands right on the number.

Say you take a team at +2.5 and the game ends with them losing by 3. You lose. At +3 you push. At +3.5 you win. The only games that change are the ones decided by exactly 3.

Now do the same thing around 9. Moving from +8.5 to +9.5 only matters when the margin is exactly 9, which happens in maybe 1% or 2% of NFL games. Moving from +2.5 to +3.5 matters in about 14% to 15% of them.

Same half point on paper. Very different value in practice.

A simple way to think about it:

• Through 3 in the NFL: a half point shifts win probability by several percentage points.
• Through 7: still meaningful, a bit less.
• Through a dead number like 5, 8, 9 or 12: close to nothing.

That is why, when a pick is posted at -3, the line matters so much. -3 and -3.5 are not neighbors. They are different bets.

Buying points

Most books let you buy a half point for extra juice. The standard price is around 10 cents per half point, so -3 at -110 becomes -2.5 at -120.

Whether that is worth it depends entirely on where the half point sits.

• Buying off 3 or onto 3 in the NFL is the one spot where a purchase can make sense, and books know it. Many charge more to cross 3 and 7, often 20 to 25 cents instead of 10.
• Buying across a dead number is almost always a bad trade. You pay 10 cents for a half point that rarely lands.
• In college, key numbers are weaker, so the fair price of a half point is lower. Paying NFL prices for college points is usually a loss.

The rule: only buy a half point when you know roughly how often the game lands on that number, and the price you pay is lower than what that half point is worth.

How this shows up on the site

When a pick moves across a key number, the line history on that pick will show it. A spread that goes from -2.5 to -3 has moved a lot more than one that goes from -8.5 to -9, even though both are a half point.

It is also one reason Sean shops three books before posting. If one book is still hanging -2.5 while the others sit at -3, that is the one marked best, and it is a real difference, not a rounding error.

The short version

• NFL margins cluster on 3, 7, 6, 10, 14 and 4. College on 3, 7, 10, 14, 4 and 17.
• A half point is only worth what the number it crosses is worth.
• 3 is the biggest number in football. 7 is next.
• Buy points rarely, and only across a key number at a fair price.