How accurate are NFL spreads? To understand that, we can review some basic statistics regarding 1,536 regular season NFL games from 2012 to 2017. The median spread of these games was 4, the median outcome was 27-17. Of those games, the favorite won 66% of the games, which is somewhat lower than college basketball.
The median variance against the spread was 8, but as you can see below the variance ranged from many games less than 5 points (i.e., very accurate spreads) to games off by more than 30 points (i.e., very inaccurate spreads).
So how accurate are NFL spreads? Pretty accurate but not perfect.
Gamblers Analytics 