When should you change tennis balls? The five concrete signs you can rely on

The five concrete signs that your tennis ball needs to be replaced

You don't need a pressure gauge or laboratory equipment. You need a hard surface, a regular tape measure, and 30 seconds. Here's what to look for, in prioritized order:

1. The bounce is low and dull. This is the first sign and the most reliable. A fresh tennis ball, when dropped from 254 cm, should bounce back 134-147 cm according to ITF standards. If the ball bounces significantly below 100 cm from the same height, the pressure has dropped enough to affect play.

2. The sound has changed. A crisp hit on a new ball produces a dry, clear pop. A worn ball gives a soft, dull sound. The difference is audible even to a mediocre ear. If in doubt, listen to a new tube next to an old one – the difference is usually unmistakable after a few bounces.

3. The felt cover is scruffy and has flat spots. The yellow felt should be even and slightly fuzzy. When it becomes smooth, has areas where the bare rubber shows through, or has matted up into hand-sized tufts, the ball has lost a significant part of its aerodynamic grip. The ball will fly differently – typically longer and flatter, because there is less air resistance.

4. The ball feels heavy or damp. The felt cover absorbs moisture from the court surface, from grass after rain, and from sweaty hands. A ball that weighs significantly more than a fresh ball is saturated with moisture – and moisture breaks down the glue between the felt and the rubber core faster than anything else.

5. The ball looks flat when it's still. A fresh ball is perfectly round. A ball with significant pressure loss can look slightly oval when resting on a flat surface, especially if it has been in a certain position for a long time. It's not always visible, but if it is, the ball is clearly below the FIP/ITF minimum.

The 30-second bounce test you can do

The fastest way to assess a tennis ball is the same test used by the ITF – just without the official equipment. You will need:

• A hard surface (concrete, tiles, hard wood – not carpet or soft linoleum)
• A measuring rod or tape measure for 250 cm
• The ball you want to test, preferably also a fresh ball as a reference point

Hold the ball at a height of 254 cm (bottom of the ball at the mark) and drop it – the ball must not be thrown. Measure how high it bounces back. Here is the interpretation:

Most recreational players are surprised by how quickly a ball falls out of the top range. It usually happens much faster than they expected.

What do the ITF and pros say?

The professional world has an extremely clear answer on when tennis balls should be changed. According to the ITF's rules and the standard used on the ATP and WTA tours, balls are changed for the first time after seven games, and then every nine games thereafter. This is not because the ball is unusable after 9 games – it's because the ball has moved out of the optimal zone.

In numbers: a professional game lasts approximately 6-12 minutes. So 7 games is less than an hour. 9 games might be an hour and a half. On the professional tour, in other words, a ball is active for a maximum of 90-120 minutes before it is replaced – and these are balls of absolute top quality to begin with.

How long between changes for recreational players?

Recreational players cannot follow the pro rule. It would be unrealistically expensive. But it is worth having a realistic benchmark. Here is a common assessment based on reported patterns in the Danish tennis world:

These numbers are not laboratory data, but estimates built on commonly reported consumption patterns and the physics that apply to pressurized rubber cores. The variation between brands is typically exaggerated in marketing materials – more on that in the article about why balls lose pressure.

What makes a ball die faster?

If your balls seem to die much faster than those at the neighboring club, it's not bad luck. It's typically one of these factors:

Hard court versus clay. Hard court is harder on the felt cover than clay or grass. The same ball can last 40-60 percent longer on clay than on concrete.

Aggressive hitting style. Heavy topspin balls and powerful flat shots stress the rubber core harder than soft slices and control tennis. Pressure drop is mechanically accelerated every time the ball is heavily deformed.

Temperature and storage. Balls left in a hot car trunk, in direct sunlight, or in an unheated conservatory in winter lose pressure and elasticity faster. Heat accelerates diffusion, cold makes the rubber stiff and easily cracked.

Moisture. Moisture breaks down the glue between the felt and the core. A ball that has been wet even once is often lost on the felt side – even if the pressure is still fine.

Time in an opened tube. An opened tube of padel balls is typically noticeably softer after a week even without use – the same principle applies to tennis balls, just a little slower because the initial pressure is higher.

How do you postpone the "death" of the ball?

The single most effective thing you can do is to stop the passive pressure drop between playing sessions. This is what kills most balls – not the play itself.

Three levels of effectiveness:

• Level 1 (free): Put the ball back in the tube with the lid on after playing. Approximately halves passive diffusion. Tubes are not airtight, but they are much better than nothing.
• Level 2 (some equipment): Store the balls at 18-22 degrees, away from direct sunlight, and always dry. This provides an additional 20-40 percent longer lifespan.
• Level 3 (active pressure storage): Store the balls in a pressurized environment that matches the internal pressure – approximately 14 PSI for tennis balls. When there is no pressure gradient, nothing diffuses out. This is the principle behind Pressurebox Pro. However, once the balls are "dead" on the felt side, it doesn't help – so pressure storage extends the usable life, but doesn't solve everything.

If you want to delve deeper into the tennis economics of this, the full calculation of what tennis balls cost annually is available. It's often more than people think. And if you want to know how long balls can actually last with good storage, we have the guide to tennis ball lifespan.