Power ratings are the foundation of systematic sports betting — a numerical representation of each team's true strength that lets you generate your own spread and compare it objectively to the sportsbook's line.
A power rating is simply a number assigned to each team that represents their quality relative to an average opponent. In the NFL, a team rated at +7 would be expected to beat a team rated at 0 (average) by 7 points on a neutral field. Adjusting for home field and other situational factors gives you a projected spread — your independent price before seeing the book's number.
How to Build a Basic Power Rating
Start with a simple efficiency-based formula: offensive points per game minus defensive points per game, adjusted for opponent strength. In the NFL, replacing raw points with EPA (expected points added) per play gives a more predictive rating because it's less dependent on game script and turnover luck.
For each team, assign a season-to-date power rating. Assign a weight to recent performance (last 4–5 games) versus full-season data — typically 40% recent, 60% full-season — to capture both current form and established quality.
Generating a Projected Spread
Take the difference between two teams' power ratings. Add a standard home-field adjustment (3 points in NFL). The result is your projected spread. If Team A is rated +8 and Team B is rated +3, and Team A is at home, your projected spread is: (8 - 3) + 3 = +6 in Team A's favor.
If the book posts the game at Team A -4, that's a 2-point gap from your projection — worth evaluating as a potential value bet.
Refining Ratings With Situational Adjustments
Raw power ratings don't account for specific circumstances. Overlay adjustments for rest advantage, injury impact, weather, and opponent familiarity. Build these into a secondary rating adjustment rather than into the base power rating, so you can isolate situational effects separately.
Log your projected spreads, compare them to posted lines, and track how accurate your power ratings are over time with Oddible.
