How Our Tennis Elo Ratings Work

Official rankings tell you who has points. They don't always tell you who's playing well right now. A guy can defend a big title for months and sit at #4 while looking nothing like a #4 on court.

That's the gap Elo fills. It updates after every match. Beat someone better than you, you move up. Lose to someone you should beat, you move down.

We run it for every ATP and WTA player on the site. Same number feeds the ladders on ATP home and WTA home, the charts on player pages, and the predictions on head-to-heads.

Four Ratings, Not One

Everyone starts at 1500. From there we keep four numbers:

Overall — everything. Hard, Clay, Grass — surface-specific. Carpet gets folded into hard.

A clay specialist can look average overall and still crush you on dirt. The surface splits are there so the prediction doesn't pretend hard-court form is clay-court form.

What Happens After a Match

Before we move anyone's rating, we build an effective rating for that match:

70% overall + 30% surface

So one weird hard-court result doesn't rewrite a clay player's whole story, but surface form still counts.

From there it's standard Elo math (400-point scale). Expected win probability from the rating gap, then the winner gains what the loser loses. How much they move depends on a few knobs:

Grand Slams move ratings more than 250s. Masters/1000 and Finals sit in between. Clay and grass results get a slight bump versus hard. We also look at a short window of recent form, and a straight-sets thrashing moves the needle a bit more than a five-set grind. Retirements and walkovers stay neutral—no free Elo from a medical timeout.

Base K-factor is 32. Same idea as chess Elo: higher K means ratings jump around more.

What About Players Who Disappear?

If someone stops playing, they shouldn't look like an active threat forever. After 60 days with no matches, ratings start drifting back toward 1500—about 5% per month, capped over a year. Keeps retired or injured names from polluting the prediction pages.

Where You'll See It

On every head-to-head page there's a match prediction that uses this exact 70/30 blend for the surface you pick. Flip from Hard to Clay and the favorite can change. Same model shows up on upcoming matches and match pages, so the number isn't different depending which screen you're on.

Player profiles have the Elo history chart next to the official ranking chart. Toggle Elo on ATP or WTA home if you want the full ladder.

Elo Isn't the Whole Story

A rating gap on a slow clay court is a different matchup than the same gap on a fast hard court. That's why we also built a Court Pace Index—so you can see how the court is playing, not just who's rated higher.

Elo is a prior. Form, history, and court speed still matter. We put all of them on the same pages so you don't have to pretend one number is enough.