Strength of schedule: why some records are harder than others
Two teams finish 8–4. One played the three best teams in the league twice each. The other mostly played teams near the bottom. Their records look identical, but almost everyone would agree the first team had the harder job.
Strength of schedule puts a number on that difference. This guide shows how to calculate it, how the well-known versions work, and how to use it in your own league.
The simple version: your opponents' winning percentage
The most common measure is the combined winning percentage of every opponent you played. Count an opponent once for each time you played them.
Strength of schedule = Opponents' total wins ÷ Opponents' total games
Worked example
Two teams each played four games. Here are their opponents' records:
| Team A's opponents | Record | Team B's opponents | Record |
|---|---|---|---|
| Opponent 1 | 9–3 | Opponent 5 | 10–2 |
| Opponent 2 | 7–5 | Opponent 6 | 10–2 |
| Opponent 3 | 6–6 | Opponent 7 | 8–4 |
| Opponent 4 | 2–10 | Opponent 8 | 7–5 |
| Total | 24–24 (.500) | Total | 35–13 (.729) |
Team A faced an average schedule (.500). Team B faced opponents who win nearly three games in four (.729). If both teams went 3–1, Team B's record is clearly the more impressive one.
Leave out the games against you
There's a catch in the simple version. Each opponent's record includes the game they played against you. If you beat a strong team, you made their record worse, which makes your own schedule look easier than it was.
The fairer method removes those games first. If Opponent 1 is 9–3 but one of the losses was to Team A, use 9–2 (.818) when rating Team A's schedule. In a long season this changes little, but in a short league it can matter.
RPI: the formula college basketball used
The Rating Percentage Index mixes your own record with your schedule. NCAA men's basketball used it for decades to help pick and seed its tournament teams, until it was replaced by the NET ranking from the 2018–19 season.
RPI = 0.25 × WP + 0.50 × OWP + 0.25 × OOWP
- WP is your own winning percentage.
- OWP is your opponents' winning percentage (leaving out their games against you).
- OOWP is your opponents' opponents' winning percentage.
Example: a team with WP .700, OWP .550 and OOWP .520 has an RPI of 0.175 + 0.275 + 0.130 = .580.
Notice that three-quarters of the RPI comes from the schedule, not the team's own results. That was one of the main criticisms of it, along with ignoring the score of each game.
Strength of schedule in the NFL
The NFL uses the simple opponents' winning percentage in two places:
- The draft. When teams finish with the same record, the team with the easier schedule picks first, on the idea that it is the weaker team.
- Playoff tiebreakers. Strength of schedule, and a related figure called strength of victory (the combined record of the teams you beat), are among the later steps used to separate teams level on record.
For more on how leagues separate level teams, see our tiebreakers guide.
Where strength of schedule can mislead
- Early in a season, every record is based on a handful of games, so schedule strength jumps around a lot.
- It goes in circles. Your opponents' records depend on their own schedules. A team that looks strong may simply have played weak opponents. OOWP and rating systems like Elo try to handle this.
- It ignores margins. A one-point loss and a heavy defeat count the same. Pythagorean expectation is a good companion if you also want to look at points scored and allowed.
- Home and away are usually not counted, even though home advantage is real in most sports.
How to use it in your own league
- List every opponent each team has played, once per game.
- Add up those opponents' wins and games (and draws, using the same rule you use for the table).
- Remove each opponent's games against the team you are rating.
- Divide wins by games to get a percentage, and compare it with the league average of .500.
A team with a schedule well above .500 has had a harder run than its record suggests. A team well below has had an easier one. That's useful when two teams are level, when you're seeding a playoff, or just for an argument with friends.
Quick takeaways
- Strength of schedule is usually your opponents' combined winning percentage.
- Remove games against the team you're rating for a fairer number.
- RPI blends your record (25%) with your schedule (75%).
- Use it alongside your record, not instead of it.
Work out each opponent's percentage fast: enter their record in Win% and it gives the winning percentage straight away.