Soccer ball diameter by size

A full-size soccer ball is about 8.5 to 8.8 inches across, or 21.6 to 22.3 cm. That is the answer, and the reason it takes a page to give is that no governing body publishes it. IFAB's Law 2 specifies a size 5 ball by circumference — between 68 cm and 70 cm — along with its weight and its pressure. Diameter never appears, so every diameter figure you find anywhere, including on this page, is circumference divided by pi.

Which is fine, and worth saying out loud, because it explains why different sites quote slightly different numbers. They are rounding the same division differently. If you need a figure for a school project, a storage rack or a goal-mouth calculation, the derived range above is as exact as the underlying specification allows.

Where the circumference figures come from

Two sources, and they cover different sizes.

• IFAB's Law 2 covers the size 5 only: circumference between 68 cm and 70 cm, weight between 410 g and 450 g at the start of the match, and pressure equal to 0.6 to 1.1 atmosphere at sea level — which the Law itself states as 8.5 to 15.6 lbs per square inch.
• AYSO's published size table covers the youth sizes by age division: size 3 at 23.0 to 25.0 inches circumference and 10 to 12 ounces, size 4 at 25.0 to 26.5 inches and 12 to 14 ounces, size 5 at 26.5 to 28.0 inches and 14 to 16 ounces.
• The FA's Futsal Law 2 specifies futsal separately and more tightly: circumference not less than 62 cm and not more than 64 cm, weight 400 to 440 g, and a controlled first rebound of 50 to 65 cm when dropped from 2 m.

The size 5 ranges differ slightly between sources: Law 2's 68-70 cm is 26.8-27.6 inches, while AYSO publishes 26.5-28.0 inches for its 14U and older divisions. Both are real; Law 2 is the match specification and AYSO's is the wider band a youth league will accept. The derived diameters above use Law 2 for size 5 because that is the tighter, official figure.

The full chart, with the age each size belongs to

Two things in that table surprise people. The first is how small the jump is: a size 4 and a size 5 are less than half an inch apart in diameter, which is why the change feels like a weight change rather than a size change — up to four ounces, or roughly a third heavier at the top of each range. Size 4 vs size 5 soccer ball covers that transition in full.

The second is where the futsal ball sits. By diameter it lands between a size 3 and a size 4, but it weighs almost as much as a size 5 — which is exactly the point. A futsal ball is heavy for its size and built with a damped bounce so it behaves on a hard floor. Futsal ball vs soccer ball has the side-by-side.

How to check a ball you already own

Measure the circumference, not the diameter. A tape measure around the widest part of the ball is a measurement you can actually take; measuring across a sphere by eye is not. Wrap the tape around the ball through two seams, keep it in one plane, and read the number — then divide by 3.14 if you want the diameter.

One caveat that matters more than the measurement: a soft ball reads small. Pressure changes the circumference, which is why Law 2 specifies the pressure alongside the size and why a ball should be checked at its stated inflation before anyone concludes it is the wrong size. A pen-style gauge reads 0 to 20 psi and is the cheapest way to settle it — soccer ball PSI chart by size has the target figures, and how to inflate a soccer ball covers doing it without wrecking the valve.

The size is also usually printed on the ball itself, next to the valve or on a panel. Checking the print beats measuring in almost every case — the reason to measure is a ball with the print worn off, or a suspicion that a ball sold as one size is actually another.

Why the official documents use circumference

Because it is the measurement you can take on a real ball without crushing it. A diameter requires calipers and a rigid object; a circumference requires a tape and a sphere. FIFA's own certification makes the same choice: of the seven laboratory tests every certified ball must pass, one is circumference — alongside weight, roundness, bounce, water absorption, loss of pressure, and shape and size retention. Diameter is not among them.

Roundness being a separate test is the other reason diameter is an awkward spec. A ball is not a perfect sphere, and a certified ball's roundness is checked precisely because it varies. A single diameter figure implies a precision the object does not have, while a circumference range tolerates it. What the FIFA quality marks mean covers how the three marks differ.

The practical version

If you are buying rather than calculating, diameter is not the number to shop on — the printed size is. Size 3 through U8, size 4 from U9 through U12, size 5 from U13, with the league's own rules overriding all of it if they say otherwise. How to choose a soccer ball is the buying guide, and the ball hub carries the full size-by-age chart with the picks at each size.

If you are calculating — for a storage bin, a shelf, a goal-mouth drawing or a homework question — use 22 cm or 8.7 inches for a size 5 and you will be within a couple of millimeters of any ball you meet. For a size 4 use 21 cm, and for a size 3 use 19.5 cm. A size 1 skills ball is about 15 cm, and Select sells its size 1 as a mini ball rather than a match ball, which is the right way to think about it.