Tennis Quotient

Rate professional tennis players by whom they beat and whom they lost to. Then compare any two players on the same tour, with every step of the math shown.

Coming soon to the App Store

For iPhone. No account, no ads, no tracking.

The idea

A win over a top-10 player should count for more than a win over a player ranked 300th, and a loss to a low-ranked player should cost more than a loss to a top-10 player. Tennis Quotient gives every match points based on the result and the opponent's rank on the ranking list in force when the tournament started. A player's value is their average points per match. To compare two players, the app uses Cohen's d, a standard measure of how far apart two averages are, with a confidence interval that shows how precise the comparison is.

Opponent rank	Win	Loss
1 to 10	+2	−0.15
11 to 50	+1	−0.33
51 to 99	+0.66	−0.5
100 to 149	+0.5	−0.66
150 to 199	+0.33	−1
200 or worse, or unranked	+0.15	−2

You can edit this table in the app and save your own version. The original always stays available.

What you see in the app

Matchup result screen showing Cohen's d, its confidence interval and each player's average points — How far apart two players are, with Cohen's d.

List of every match counted, with the opponent's rank at the time and the points earned — Every match counted, with the opponent's rank at the time.

Tuning screen with switches for retirements and walkovers and the editable points table — Settings and the points table you can edit.

Your choice of matches

The last 52 weeks by default, or the last few matches, weeks or months, or a player's full record. Turn on recency weighting to make older matches count less.

Nothing hidden

Each comparison lists the matches it used: date, event, round, opponent, the opponent's rank at the time, win or loss, and the points earned.

Clear about the data

Men's results from the Association of Tennis Professionals (ATP) tour start in 2007. Women's results from the Women's Tennis Association (WTA) tour start in 2024. The data is built into the app and is updated with new app versions. The app shows its date and lists known gaps.

Private by design

Tennis Quotient has no account, no ads and no tracking. It works offline and collects no personal information. Your saved comparisons and settings stay on your iPhone. Read the privacy policy.