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Last Updated: January 21, 2019

Betting the NFL

Introduction

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.

Unless otherwise stated, the source of this data is every NFL game played from the 2006 season through and including week 1 of the 2018 season. This is a total of 3,220 games. The data is available for free at Australia Sports Betting.

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.

The following table shows the probability of winning, losing, and pushing according by various breakdowns.

Point Spread Bets in the NFL

Bet Wins Losses Pushes Win Rate Std. Dev. N.S.D. Return
All home 1,484 1,680 56 46.90% 1.26% -2.46 -10.28%
All away 1,680 1,484 56 53.10% 1.26% 2.46 1.34%
All favorite 1,488 1,617 56 47.92% 1.27% -1.64 -8.36%
All underdog 1,617 1,488 56 52.08% 1.27% 1.64 -0.57%
Home underdog 492 520 20 48.62% 2.22% -0.62 -7.05%
Home favorite 968 1,125 36 46.25% 1.55% -2.43 -11.51%
Away underdog 1,125 968 36 53.75% 1.55% 2.43 2.57%
Away favorite 520 492 20 51.38% 2.22% 0.62 -1.87%
Home pick 24 35 0 40.68% 9.21% -1.01 -22.34%
Away pick 35 24 0 59.32% 9.21% 1.01 13.25%
All 3,164 3,164 112 50.00% 0.89% 0.00 -4.47%

Explanation of column headings:

  • Bet: Type of bet
  • Wins: Number of wins against point spread
  • Losses: Number of losses against point spread
  • Pushes: Number of pushes against point spread
  • Win Rate: Ratio of wins to bets resolved
  • Std. Dev.: One standard deviation in the mean of the win rate, assuming every bet had a theoretical chance of winning of 50%.
  • N.S.D: Number of standard deviations that the actual results differ from an expected win rate of 50%.
  • Return: Ratio of money won (lost = negative) to money bet, assuming laying 11 to win 10.

Over/Under Bets

The following table shows the results of under and over bets. It shows both had nearly a 50% chance of winning. In face, over 3,220 games the over won just two more times than the under. I thought under bets would have performed better, but I've been wrong before.

Under and Over Bets in the NFL

Bet Wins Losses Pushes Win Rate Std. Dev. N.S.D. Return
Over 1,586 1,576 58 50.16% 1.26% 0.13 -4.17%
Under 1,576 1,586 58 49.84% 1.26% -0.13 -4.76%

Money Lines

The following brief table shows the result of money line bets.

Money Line Bets in the NFL

Bet Return
Underdog -3.91%
Favorite -6.24%
All -5.08%

The next table shows the actual and estimated probability of winning for underdogs of 1 to 14.5 points. Obviously, the probability of the favorite winning would be 100% less the probability of the underdog winning. The estimated probability of winning uses logistic regression to smooth out the ups and downs.

Probability of Winning by Point Spread in the NFL

Spread Games Wins Actual
Probability		 Estimated
Probability		 Fair
Line
1 139 69 49.6% 46.4% 115
1.5 88 43 48.9% 44.6% 124
2 126 51 40.5% 42.9% 133
2.5 224 98 43.8% 41.1% 143
3 517 235 45.5% 39.4% 154
3.5 279 107 38.4% 37.7% 165
4 157 59 37.6% 36.1% 177
4.5 128 47 36.7% 34.4% 191
5 89 23 25.8% 32.8% 205
5.5 118 38 32.2% 31.3% 220
6 133 45 33.8% 29.7% 236
6.5 147 42 28.6% 28.3% 254
7 220 51 23.2% 26.8% 273
7.5 146 36 24.7% 25.5% 293
8 65 14 21.5% 24.1% 315
8.5 52 16 30.8% 22.8% 338
9 58 13 22.4% 21.6% 363
9.5 48 6 12.5% 20.4% 390
10 104 19 18.3% 19.3% 419
10.5 61 15 24.6% 18.2% 450
11 41 4 9.8% 17.1% 483
11.5 22 4 18.2% 16.1% 519
12 13 3 23.1% 15.2% 558
12.5 25 4 16.0% 14.3% 599
13 34 6 17.6% 13.4% 644
13.5 36 4 11.1% 12.6% 692
14 36 3 8.3% 11.9% 743
14.5 12 1 8.3% 11.1% 798

If you want to estimate the probability of winning of an underdog of more than 14.5 points, the formula is e^(-0.14324*s)/(1+e^(-0.14324*s)), where s is the point spread. To convert any probability under 50% to a fair money line, the formula is 100*(1-p)/p, where p is the probability of winning. To convert any probability over 50% to a fair money line, the formula is -100*p/(1-p).

Parlays

Here is my quick advice on parlays:

  • If you bet off the board, either do a pick-3 or mix in one leg that isn't at the standard -110 odds, to get off the lousy parlay odds table, and force a fair calculation.
  • On parlay cards, try to capture as many points as you can compared to the "off the board" point spread.

I have much more information about parlays in my page on Parlay Bets in the NFL.

Teasers

Here is my quick advice on teasers:

  • If you bet off the board, the best odds are at Jerry's Nugget.
  • Try to cross the 3- and 7-point margin of victories with the extra points.
  • Teaser cards are a sucker bet.
  • If you must bet a teaser card, I recommend the the Ties Win Teaser Card at any Caesars sports book.
  • On teaser cards, try to capture as many points as you can compared to the "off the board" point spread.

I have lots more information about teasers in my page on Teaser Bets in the NFL.

Buying Half a Point off the Spread

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 (MOV) in the NFL. To be specific, the margin of victory is three 14.5% of the time, and seven 9.2%, as the following table shows.

Margin of Victory in the NFL

MOV Probability
0 0.2%
1 3.7%
2 3.8%
3 14.5%
4 5.2%
5 3.4%
6 6.2%
7 9.2%
8 3.6%
9 1.7%
10 5.6%
11 2.5%
12 1.5%
13 2.9%
14 4.8%
15 1.5%
16 2.1%
17 3.1%
18 2.3%
19 1.1%
20 2.4%
21 3.2%
22+ 15.7%
Total 100.0%

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 extra half point, to equal the expected loss of 4.54% laying 11 to win 10. The bottom line is you should definitely buy the half point off of three, if you can, and it is marginally good off of seven. Anything else and it is a bad value.

Buying a Half Point Off the Spread

Spread Fair Price
3 128.1
4 116.9
7 121.9
10 117.9
14 117.0

Buying Half a Point off the Total

The overall fair number of basis points to pay for a half point off the total is 8.12. In other words, you should be indifferent to laying 11 to win 10 and laying 118.12 to win 10 with an extra half point. The following table shows my suggested fair price to pay to capture totals from 30 to 60. By "capture" I mean turn a push into a win or a loss into a push. If you have to lay 10 basis points for the half point, my table shows that it is never a good value, although sometimes it is close. An explanation of the column headings follows the table.

Buying a Half Point off the Over/Under in the NFL

Total
Points		 Num. in
Sample		 Probability Fair
Price
30 89 0.027640 6.58
31 48 0.014907 3.50
32 42 0.013043 3.06
33 102 0.031677 7.58
34 83 0.025776 6.13
35 52 0.016149 3.80
36 74 0.022981 5.45
37 120 0.037267 8.98
38 63 0.019565 4.62
39 62 0.019255 4.54
40 105 0.032609 7.81
41 121 0.037578 9.05
42 48 0.014907 3.50
43 126 0.039130 9.45
44 123 0.038199 9.21
45 82 0.025466 6.05
46 64 0.019876 4.69
47 113 0.035093 8.43
48 98 0.030435 7.27
49 61 0.018944 4.47
50 81 0.025155 5.98
51 119 0.036957 8.90
52 74 0.022981 5.45
53 51 0.015839 3.72
54 66 0.020497 4.84
55 85 0.026398 6.28
56 25 0.007764 1.81
57 63 0.019565 4.62
58 58 0.018012 4.24
59 40 0.012422 2.91
60 18 0.005590 1.30

Key to column headings:

  • Total Points = Total point scored in game
  • Num. in Sample = Number of times this total appeared in a sample of 3,220 games.
  • Fair Price = My fair number of basis points to pay to capture this number (after a lot of math)

My page on alternate point spreads shows what it is worth to buy or sell up to seven points off the spread. That page has not been updated with the latest data yet.

Example

Assume the over/under on a game is exactly 43 points. My table shows the fair number of basis points to pay to capture the 43 is 9.45. This means you should be indifferent to laying 110 on the under 43 or over 43 to laying 119.45 on the under 43.5 or over 42.5.

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