This page explains exactly how the Power Rankings Today NFL power rankings are calculated: the Elo rating, recent form, box score efficiency, the PRT Score that combines them, and the limits of the model. Nothing on the site is adjusted by hand.
1. Elo Rating
Every team carries an Elo rating. League average is 1500. After each game the winner gains points and the loser gives up the same amount, so the league total never changes. Ratings are rebuilt from scratch, in date order, every time new results arrive.
| Setting | Value | Why |
|---|---|---|
| K factor | 20 | How far one game can move a rating. 20 is the standard value for the NFL. |
| Home field | 55 Elo points | About two points on the scoreboard. |
| Margin of victory | ln(margin + 1), scaled | Bigger wins count more, but with diminishing returns, so one blowout cannot dominate. |
| Favorite correction | 2.2 / (Elo gap x 0.001 + 2.2) | Stops strong teams from inflating their rating by beating weak teams by a lot. |
| Season carryover | 75% | Each team starts the season with 75% of last season’s gap from 1500. |
The expected result for the home team is 1 / (10-d/400 + 1), where d is the home team’s Elo plus 55 minus the away team’s Elo. A team that beats that expectation gains points; a team that falls short loses them.
2. Recent Form
Form is the total Elo change over a team’s last four games. It catches teams that are getting better or worse faster than their season long rating shows.
3. Box Score Efficiency
Efficiency is built from the box score of every regular season game:
| Part | Share | What it measures |
|---|---|---|
| Net yards per play | 45% | Yards per play gained minus yards per play allowed. The most stable predictor of future results. |
| Scoring margin | 30% | Points scored minus points allowed, per game. |
| Third down net | 15% | Third down conversion rate minus the rate allowed. |
| Turnover margin | 10% | Takeaways minus giveaways, per game. Kept small because turnovers swing a lot from week to week. |
Until box scores cover at least 80% of a team’s games, its efficiency uses scoring margin alone.
4. The PRT Score
Each part is placed on a fixed 0 to 100 scale so scores can be compared from week to week, then blended:
| Part | Weight | Scale |
|---|---|---|
| Elo rating | 55% | 1250 = 0, 1750 = 100 |
| Recent form | 20% | -80 = 0, +80 = 100 |
| Efficiency | 25% | Blend above, 0 to 100 |
Teams are ranked by PRT Score, with Elo as the tiebreaker, and grouped into tiers: Title Contenders (70 and up), Playoff Teams (60 to 69.9), In the Hunt (50 to 59.9), Need a Run (40 to 49.9) and Long Shots (under 40).
5. Win Chances and Projections
The win chance for any game uses the same Elo expectation, including home field, with each team’s current rating. A team’s projected record adds the win chances of all its remaining games to the wins it already has. Projections only appear when the full remaining schedule is known. Win chances are model context, not betting advice.
6. Updates and Weekly Editions
- Ratings refresh about every 30 minutes on game days and every 6 hours otherwise. The time of the last update is shown on every rankings page, in Eastern Time.
- Each Tuesday morning, after Monday Night Football, the full order is saved as that week’s edition, along with each team’s note, form and efficiency. Saved editions are never rewritten.
- The live page is labeled for the week it is published for: rankings built after the Week 7 games are the Week 8 rankings.
7. Data Sources
Scores, schedules and box scores come from a licensed live sports data feed. Ratings, notes and analysis are calculated and written by Power Rankings Today. We do not copy rankings from other sites.
8. Known Limits
- The model does not know about injuries, trades or quarterback changes until they show up in results.
- Early in a season, ratings lean on last season through the carryover, and move quickly as games are played.
- Small samples make efficiency numbers noisy in the first few weeks.
Spot a wrong score or have a question about a number? Email Lisa Smith at iamlisa147@gmail.com. See the live results on the NFL power rankings page.