Key spread numbers
The lumpy nature of the NFL’s margins leads to certain point spreads being stickier than others. Fully 40 percent of NFL games end with a margin of exactly 3, 6, 7, 10, or 14. A bookmaker who opens a team at –7 will require significantly more action to move the spread to –7-1/2 because it’s such a major stopping point for game margins.
And 3 points is another key number. Fully 8 percent of NFL home teams win by exactly 3 points, which means there’s a huge difference in betting on a home favorite at –2-1/2 versus –3-1/2, even though they’re only an extra point apart. If this were a game scored one point at a time (like volleyball perhaps), the oddsmaker would be indifferent about moving the point spread smoothly up or down as action becomes unbalanced. Not so with football.
The lesson: Shop around. When you’re thinking of betting a side that’s lined in the neighborhood of +3 points, shop around and see if you can find +3-1/2. And by the same token, as an underdog bettor, you can’t consider +2-1/2 and +3 to be in the same probability neighborhood as you might think of +4-1/2 and +5.
Betting at +5 rather than +4-1/2 will almost never matter. Five is an incredibly rare game margin. In the last 20 years, there have been 77 games lined at +4-1/2, and in only one case (1.2 percent) did a team getting 4-1/2 points lose the game by exactly 5 points. That means the difference between those two-point spreads is almost nothing. In fact, if you were betting on a team at +5 and you had a chance to sell a half point, it just might be worth it.
Selling points
Selling points is an action you can take with some bookmakers when you’re finalizing a point spread bet. By giving back a half point on your point spread (for example, from +5 to +4-1/2), the bookmaker gives you a more advantageous payout schedule. (For example, instead of a –110 bet, or risking $110 to win $100, the bookmaker will ask you to risk $102 to win $100 as compensation for your half point.)
Let’s look at the same half-point difference between +2-1/2 and +3. There have been 152 games in the last 20 years where the home team was a +2.5 underdog. In 13 (7.5 percent) of those games, the home team lost by exactly 3 points. So, you might say for underdog bettors, the half-point that moves you to 3 is worth 7 times as much as the half point that moves you to 5.
Is it worth it? Let me work it.
If you treat NFL margins and total score patterns as actual probabilities for the future, they become good-use cases for putting our knowledge of break-even winning percentage to work for us to compare two bets.
In this case, we’re contemplating selling a half point back to the bookmaker in exchange for a more advantageous set of payout odds. Again, the bookmaker has offered to mover our odds from –110 to –102 if we’d be willing to move from +5 down to +4-1/2. Should we do it?
At –110, the break-even winning percentage is 52.38 percent. At –102 the break-even winning percentage becomes 50.2 percent. It might seem like small potatoes, but professionals are constantly on the lookout for advantages like this, as they would welcome a 2.18-percent edge because they know — like casinos — that tiny edges make a big difference in the long run. So now we look at what we lose when we give away that half point. As I discussed above, a 5-point margin is extremely rare. It only impacted 1 out of 77 games lined at +4-1/2, and a home team losing by 5 points at any spread has only happened about 1.5 percent of the time. But since the 2.18-percent advantage gained is more than the 1.5-percent advantage lost, you should make that bet. It’s a positive EV play, so sell that half point!
What about moving from +3 –110 down to +2-1/2 at –102 odds? We already know that at –110 we need to win 52.4 percent of the time to break even, and –102 gets us to 50.2 percent. But that 2.18-percent advantage we gain is outweighed by the fact that at +2-1/2, we know that 7.5 percent of the time, a bet that would have previously won for us will now only push. Stick to the three points unless the bookmaker can give you a better price for moving from +3 to +2-1/2.
There is a generic rule of thumb that the correct price for moving off of a key number in the NFL is 25 odds points, or in our case, moving from –110 to +115. In other words, if a bookmaker isn’t willing to up your moneyline by at least 25 odds points (and most won’t), don’t sell that 1/2 point. There are some excellent free calculators online that can help you work through the math on buying and selling half points on NFL bets.
Moneyline betting
Oddsmakers offer the usual handicap-free moneyline bets to bettors who aren’t interested in the point spread. The only thing you need to know about NFL moneylines is that they are tied into to the key numbers I talked about in the previous section.
The table shows that a rough equivalent between an NFL moneyline and point spread (assuming –110 odds) on some key numbers.
NFL Moneylines and Point Spreads
Favorite Point Spread Moneyline Historical Straight Up Win% Underdog Point Spread Moneyline Historical Straight Up Win%
–2 –130 59% +2 +110 41%
–2-1/2 –140 58% +2-1/2 +125 42%
–3 –155 58% +3 +140 42%
–3-1/2 –175 63% +3-1/2 +155 37%
–4 –200 66% +4 +170 34%
–6 –270 72% +6 +210 28%
–6-1/2 –300 84% +6-1/2 +220 16%
–7 –330 75% +7 +250 25%
–7-1/2 –360 82% +7-1/2 +280 18%
–9-1/2 –400 76% +9-1/2 +300 24%
–10 –450 75% +10 +325 25%
These numbers are from 2013 onward to incorporate the most recent rules that had a direct impact on scoring. That means for some of the oddities you see, it’s entire possible there’s not enough data yet to smooth out the curve. And in case you’re wondering, no, it’s not an accident that the winning percentages associated with each point spread are the inverse of each other.
These are rough equivalents. While point spreads can make the odds look placid and calm on the surface, moneylines are more prone to churn beneath the waves. Moneylines don’t automatically move in perfect sync with spread moves, and it’s not uncommon for bookmakers to use the moneyline as a way to fine-tune action on either side of a game. A typical NFL Sunday might have two games where the favorites are both listed at –3 +100, but one moneyline is set at –155 and the other is set at –145. The lesson? If you’re a moneyline bettor, shop around.
