Betting the NFL
Last Update: Nov. 21, 2013
This page assumes the reader already has a good grasp of sports betting terminology. If this is not the case, I recommend reading my general page on sports betting first.
Point Spread Bets
I admit "point spread bet" is not a common term in sports betting, but I'm trying to change that. What I call a point spread bet is a basic bet against the point spread. Many people call this a "straight bet" but this term can also be used, and is printed on tickets for, money liney bets, total bets, and any other bet involving just one game. So I invite the rest of the world to adopt this term.
In the NFL home underdogs have historically done well against the spread. The following table shows the probability of winning, losing, and pushing according by various breakdowns. The table covers every game from the 1983 to 2008 seasons. The expected return is for the standard laying 11 to win 10. The expected return when laying 105 to win 100 is about 2.2% more than when laying the same odds.
Following are the result of every NFL game from the 1983 to 2008 seasons:
Overall the house edge on over bets is 5.89% and on unders is 2.98%, assuming the bettor risks $11 to win $10.
I often find what I believe to be a good bet on an underdog on the money line. The following chart shows the probability of winning by point spread, based on historical data (from the 1994 through 2012 seasons).
The following table shows the actual data. The estimated probability of winning is based on smoothing out the ups and downs. The fair money line is based on the estimated probability of winning. This table does not factor in "key numbers" in the NFL. In other words, some margin of victories are much more likely than others, especially 3 and 7. It is a much bigger handicap to be given 3.5 points compared to 2.5, thus the 3.5-point underdog is going to have a significantly lower chance of winning compared to a 2.5-point underdog. I'll leave adjustment to the reader (sorry).
To find the fair money line on a favorite, just multiply by -1. For example, a 7-point underdog shows an estimated probability of winning of 28.9%, which corresponds to a fair money line of +249. Thus, a 7-point favorite would have a 71.35% chance of winning, for a fair money line of -249.
Here is my quick advice on parlays:
I have much more information about parlays in my page on Parlay Bets in the NFL.
Here is my quick advice on teasers:
I have lots more information about teasers in my page on Teaser Bets in the NFL.
Buying Half a Point
Sometimes a sports book will let you buy a half point off the spread for total. For example, moving a point spread from +10 to +10.5. The price for this is laying an extra cents, in most cases laying 120 instead of 110. However, rarely will a sports book let the player buy onto point spreads of 3 or 7, for example moving from +2.5 to +3, because 3 and 7 are frequent margin of victories in the NFL. To be specific, the margin of victory is three 15.9% of the time, and seven 9.5%.
The following table shows the fair price to pay for most spreads and totals. For example, moving the spread from +2.5 to +3, +3 to +3.5, -3.5 to -3, or -3 to -2.5, would be buying the 3. In these cases if the favorite won by 3, or the underdog lost by 3, then it would turn a push into a win, or a loss into a push. The table shows the fair price to pay for the 3 is 20.8 cents. In other words, the bettor should be indifferent between betting +3 -110 and +3.5 at -130.8.
My page on alternate point spreads shows what it is worth to buy or sell up to seven points off the spread.
The next table shows the fair prices to pay on NFL total bets. Like point spreads, there are key numbers in totals. For example, 37 and 41 points are the two most common totals at 4.4% each. However, the key number effect is not as strong in totals as point spreads, so there is not as much variance in the fair prices.
My page on alternate totals shows what it is worth to buy or sell up to seven points off the total.