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. Comparing two players needs a monthly subscription.

New in 1.1: a History window switch (52 weeks, full history or custom), surface weighting or a same-surface-only view, and rank-adjusted values for players with few matches, which are used by default and can be switched off on the Tuning tab.

The idea

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 win over a top-ranked player earns much more than a win over a low-ranked player, and a loss to a low-ranked player costs much more than a loss to a top-ranked one. 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.

What you see in the app

Result screen showing Cohen's d, its confidence interval, Hedges' g and each player's average points per match — How far apart two players are, with Cohen's d.

Show your work: how each match is scored, then 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 the opponent-rank points choice and the switches for retirements and walkovers — Settings for which matches count and how.

Your choice of matches

Switch the history window on the matchup and result screens: the last 52 weeks, the full record, or a custom number of weeks, months or matches. Pick a surface to give matches there extra weight, or to use only matches on that surface. The history, surface and rank-adjustment settings were chosen by testing them on past matches, and the app shows how they were chosen. You can change any of them on the Tuning tab.

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

Association of Tennis Professionals (ATP) results start in 2007; some ATP events are missing from the source, and ATP Challenger events are not included. Women's Tennis Association (WTA) results start in 2024. The data is built into the app and never comes from the network. It is refreshed about weekly through App Store app updates, and the app always shows the date the data runs through. The app lists known gaps on its Data tab.

Private by design

No account, no ads, no tracking. Tennis Quotient works offline, makes no network requests for data and collects no personal information. Your saved comparisons and settings stay on your iPhone. Read the privacy policy.

Subscription

Comparing two players needs a monthly subscription, bought in the app through Apple. New subscribers can start with a one-week trial, and the App Store shows the monthly price that follows before you confirm. It renews automatically each month until you cancel it in Settings, and Apple handles the payment. Without a subscription you can still search and browse players and see each player's value. The app shows the price for your country before you subscribe. Terms of Use.