Padel ball pressure: what the FIP rules really say

What the FIP rules actually say about pressure

The International Padel Federation (FIP) covers the ball in its Rules of Padel and its Ball Certification Process. Both documents give the same pressure line: the ball must have an internal pressure "between 4.6 kg and 5.2 kg per 2.54 square cm".

Read it twice and the problem is clear. A pressure is a force over an area, and "2.54 square cm" is not a standard area. It looks like someone mixed up 2.54 cm, which is one inch, with one square inch. Even then, the rule does not say whether the figure is above outside air pressure or absolute, and that alone changes the answer a lot.

Because we cannot tell what the FIP meant, we do not convert it to psi or bar. Any number you calculate from it depends on a guess about the unit.

So where do the psi figures online come from?

Many padel pages state that padel balls are around 10 to 11 psi and tennis balls around 14 psi. We could not find either figure in any FIP document or ball maker's specification.

The tennis half is also wrong. The ITF, which writes the tennis ball rules, says a new pressurised tennis ball is typically 10 to 13 psi (70 to 90 kPa) above atmospheric pressure. The 14 psi figure appears on some pressurizer product pages, not in the ITF rules.

It may well be true that padel balls run a little lower pressure than tennis balls. Sites such as Playtomic say so. But nobody has published a sourced number, so we treat it as unconfirmed.

The padel ball spec, side by side with tennis

Why bounce matters more than the pressure number

You cannot put a gauge into a sealed ball without making a hole, and a hole lets the air out. So in practice, players and labs judge a ball by its bounce. The FIP's certification process measures rebound and suggests doing it with calibrated scales and a digital video camera.

Pressure and bounce are closely linked. As air leaks out of a pressurised ball, it bounces lower. That makes a drop test a good stand-in for a pressure gauge, as long as you compare like with like: same floor, same height, same temperature.

For a quick feel for the numbers, a new ball dropped from the 2.54 m test height comes back to 135 to 145 cm. From the top of the net, which the FIP rules set at 88 cm (34.6 in) in the centre, our scaled estimate is about 47 to 50 cm (18.4 to 19.8 in).

High altitude padel balls

At altitude, the outside air pressure is lower, so a ball pressurised for sea level plays livelier. The FIP allows a different ball with a lower rebound, 121.92 to 135 cm, for these courts.

When it applies is less clear. The Rules of Padel say "more than 1000 m". The Ball Certification Process says "above 800 m" in one place and 1,219 m (4,000 ft) in its table notes. If you play in the mountains, check with your federation or club which ball they use.

Pressureless padel balls

The FIP also allows pressureless padel balls, with an internal pressure of no more than 7 kPa and acclimatised for 60 days. Like pressureless tennis balls, they get their bounce from the rubber rather than the air, so they do not go flat the same way.

How to check your padel balls without a gauge

1. Take one ball from a freshly opened can as your reference, the same brand and model as the balls you are checking.
2. Find the flattest, hardest part of the court, away from the sand that collects near the walls and corners.
3. Hold both balls side by side with their bottoms level with the top of the net, 88 cm (34.6 in) in the centre.
4. Let go together. No push, no spin.
5. Watch the first bounce. A new ball should come up to roughly 47 to 50 cm (18.4 to 19.8 in). You are looking for a clear gap between the two balls.
6. Repeat three times, swapping hands, to rule out an uneven release.
7. Squeeze each ball. A ball that gives much more than the new one has lost pressure. Use this to back up the drop, not replace it.
8. Hit a few balls off the back glass. A flat ball dies off the wall instead of coming back to you.

Does temperature change padel ball pressure?

Yes, a little, and it shows in the bounce. Warm air pushes harder than cold air, and warm rubber is livelier. The ITF notes for tennis balls that high temperatures increase bounce height, which is why approval tests run at a fixed 20 °C (68 °F). Padel balls are built the same way, so the same applies.

We found no reliable figure for how much the bounce changes per degree, for padel or tennis. The practical rule is simple: compare balls at the same temperature. A ball from a cold car will seem flat next to one from your warm kit bag, even if they are the same age.

What happens to the pressure once the can is open?

Inside the sealed can, the balls sit in pressurised air, so there is little difference to push air out of them. Once the can is opened, the air around them drops to normal pressure, and air starts working its way out through the rubber. Putting the lid back on does not help, because the can is now at normal pressure too. Only a pressurizer, which raises the pressure around the balls again, tries to stop the leak.

Where BallCheck fits

BallCheck measures the result of pressure, the bounce, using your phone's microphone. Put the phone on the court, drop the ball from net height and it times each bounce, then compares the ball with a new padel ball on your court type. You get a score out of 100 and a call: keep, pressurize or retire. Padel floors vary a lot with sand and turf, and reference values assume lab conditions, so drop one new ball on your court first to calibrate. The free web version works in your browser today.