How long do tennis balls last? When to replace them

The short version, by situation

How long a ball lasts depends on what kind of ball it is, how hard you play and what you need from it. A ball that is too flat for a league match can still be perfect for feeding drills. This table sums up what the sources actually say, without the made up "two weeks" rule you see on many sites.

Why tennis balls lose their bounce

Most tennis balls are pressurised. The ITF says the air inside a new ball is typically 10 to 13 psi (70 to 90 kPa) above the air outside. That extra pressure is a big part of what makes the ball bounce.

Rubber is not airtight. Once the can is open, air slowly works its way out through the core, and the bounce drops with it. Play speeds this up, and so does wear: every hit flattens the ball for a moment, fluffs the felt and fatigues the rubber.

The loss is not a straight line. In Cross and Lindsey's study of 26 balls from 8 brands, most balls bounced slightly higher after a simulated wear test, some by more than 1.5%, while getting softer. An older lab thesis found machine-fatigued balls bounced higher than new ones until about 3,200 impacts before dropping off. So a ball can feel lively for a session or two and then fall away quickly.

Why do pros change balls after 7 games, then every 9?

The ITF rules let tournaments change balls "after an agreed odd number of games". The first change comes two games earlier to allow for the warm-up, when the same balls were already being hit. Nine games is the usual interval, which is why you hear "7 then 9".

The ITF's own durability test is built around the same number. It simulates nine games of play with 20 hard impacts and two minutes in an abrasion box. Afterwards, an approved ball's rebound may change by no more than 4.0 cm (1.6 in).

That tells you something useful. Even the official standard expects a ball to change over nine games. Pros want every ball to play the same, so they change long before a club player would notice a difference.

How many sets do tennis balls last?

Nobody can give you an honest number of sets, because it depends on too many things. A few patterns do hold. For matches, many players open a new can for each important match, which is a habit rather than a rule. For social play, a can can often last several sessions before the drop is easy to notice. For coaching baskets, balls stay useful until the felt is bald or the bounce is clearly uneven.

This is what makes the biggest difference.

Do tennis balls expire in the can?

Not on a fixed date, but they do age. A sealed can is pressurised, which stops the balls from leaking air the way they do once opened. Cans are not perfectly airtight forever, though, and a can that has been in a garage for years may play flat when you open it. Our guide on whether tennis balls expire covers unopened cans in detail, including how to check an old one.

Which tennis balls last the longest?

Pressureless balls last longest in terms of bounce, because there is no air pressure to lose. The ITF explains they get more of their bounce from a thicker rubber core. Cross and Lindsey found the softening that comes from air loss does not happen in pressureless balls, although two of theirs got slightly stiffer over five months as the rubber aged.

The trade off is feel. Pressureless balls are firmer, and match play uses pressurised balls. If you want a ball for a ball machine or a practice basket, pressureless is the sensible choice. Our guide to pressureless and pressurised balls goes through the differences.

Among pressurised balls, there is no independent ranking of which brand holds its pressure longest. Claims you see in ads come from the brands themselves.

How to tell when your balls are done, at the court

You do not need a lab. You need one new ball from a fresh can and a few minutes. The net is a handy drop height: the ITF rules set it at 0.914 m (3 ft) in the centre.

1. Open a new can of the same ball type, or keep one fresh ball as your reference.
2. Stand on a flat, hard part of the court, away from lines and cracks. Clay and grass both soak up bounce, so compare on the same surface.
3. Hold the old ball and the new ball side by side at the top of the net tape, bottom of each ball level with the tape.
4. Let go of both at the same moment. Do not throw or spin them.
5. Watch the top of the first bounce. From net height, a new standard ball rebounds roughly 49 to 53 cm (19 to 21 in), so you are looking for a clear gap between the two.
6. Repeat three times, swapping hands each time, so you are not fooled by an uneven release.
7. Listen too. A ball that has lost pressure sounds duller and its bounces come closer together.
8. If the old ball is clearly lower every time, retire it from matches. Keep it for practice if the felt is still in one piece.

How to make tennis balls last longer

• Close the can or put balls in a pressurizer straight after play. The less time they spend at normal air pressure, the less air they lose. Note that no independent published test has measured how much a pressurizer helps.
• Keep balls out of hot cars and direct sun. Heat helps air move through rubber, so warm storage is likely to speed up pressure loss.
• Use separate balls for practice and matches, so your match balls only take match play.
• Retire balls with split seams or bald felt. They will not bounce or fly the same, whatever the pressure.

Measure it instead of guessing

Small changes are hard to see. The ITF durability limit of 4.0 cm from a 254 cm drop works out at only about 1.5 cm (0.6 in) from net height, which is too small to spot by eye. BallCheck listens to the bounces with your phone on the floor and compares your ball with a new one of the same type, giving a score out of 100 and a clear call: keep, pressurize or retire. Reference values assume lab conditions, so test a new ball on your own court first and BallCheck will use your court as the baseline. The free web version works today in your browser.