Soccer ball PSI by size

This page exists because the honest answer is not the one people expect. There is no official PSI for a size 3 or a size 4 soccer ball, because the Laws of the Game only specify the ball used in the eleven-a-side game — a size 5. Every chart you will find online that confidently gives a single PSI for a size 3 has either copied it from somewhere or made it up.

What there is, on essentially every ball sold, is a pressure printed next to the valve by the manufacturer. That number is the answer for your ball, and manufacturers say so: Molten's own care instructions are to use a thin inflation needle to avoid damaging the valve and to inflate the ball slowly to the pressure printed on it.

What Law 2 actually says

For a size 5, the specification is precise and worth knowing in full, because it also sets the ball's circumference and weight. Law 2 requires a circumference between 68 cm and 70 cm, a weight between 410 g and 450 g at the start of the match, and a pressure equal to 0.6 to 1.1 atmosphere at sea level — which the Law itself converts to 8.5 to 15.6 pounds per square inch.

Two things follow from that. First, the legal window is far wider than most people assume: a ball at 9 psi and a ball at 15 psi are both legal and feel completely different. Second, the correct pressure is in single digits to low teens, which is why no soccer pump ever has to work hard and why a bicycle pump reading in the hundreds is the wrong tool.

Futsal is specified separately and more tightly. The FA's Futsal Law 2 sets a circumference of 62-64 cm, a weight of 400-440 g at the start of the match, a pressure of 0.6-0.9 atmosphere at sea level, and a first rebound of between 50 cm and 65 cm when dropped from 2 m — that last figure being the low bounce that defines the format.

How to find the number for your ball

1. Look next to the valve. Almost every ball has the recommended pressure printed there, usually in both psi and bar.
2. If it has rubbed off, check the manufacturer's listing for that model. Brands publish it.
3. If you cannot find it at all, treat the size 5 window as the guide — low single digits is too soft for any ball, and the mid range of 8.5 to 15.6 psi is a safe place to be.
4. Inflate slowly, with a thin needle, and stop at the number rather than at the feel.

Do not use the squeeze test as your primary measure. An adult hand cannot distinguish 9 psi from 14 psi on a size 4, and the difference is the difference between a ball that dies on the first touch and one that flies. A gauge turns guessing into reading.

Why the wrong pressure costs you a ball

Pressure is not only about feel. A ball kept under-inflated loses its shape permanently, because the panels and the carcass are designed to be held taut. A ball kept over-inflated stresses the seams. Both failures are slow and both are avoidable with a gauge, which is why a pump that reads a number is the cheapest genuinely useful thing a soccer family can own.

Bladder material decides how often you have to think about it. A butyl bladder holds air considerably longer than latex, which in practice is the difference between pumping monthly and pumping weekly. That is also why a cheap yard ball needs checking before every session and a mid-tier ball does not.

• Under-inflated: dead first touch, permanent loss of shape, the ball goes out of round.
• Over-inflated: stressed seams, a harsh ball on a cold morning, and a hard strike on a young foot.
• Correct, and checked: the ball behaves the same way every week, which is the point.

Temperature, altitude and the cold Saturday problem

Law 2's pressure figures are specified at sea level, which is a reminder that pressure is not a fixed property of a ball. Air contracts as it cools, so a ball inflated to the top of its range in a warm house will read lower on a frosty field, and a ball pumped up outside on a cold morning will read higher once it warms up indoors.

The practical version: check the pressure where you are going to play, not in the garage, and check it again in the first cold week of the season. That one habit explains most of the mid-autumn complaints that a ball has gone soft.

Storage matters for the same reason. Molten's care guidance is explicit that a ball should never be left in high temperatures or humidity — a car trunk on a hot day is the example it gives — because that costs the ball its carefully tuned shape and deteriorates the carcass.

The step-by-step is on how to inflate a soccer ball, the pump options are on best soccer ball pumps, and if the ball needs cleaning before it goes away for the winter, how to clean a soccer ball has the routine. For which size a given age should be playing with at all, start at how to choose a soccer ball.