Size 3 vs size 4 soccer ball

The short answer: U8 and below is size 3, U9 through U12 is size 4. AYSO lists the size 4 at 25.0 to 26.5 inches circumference and 12 to 14 ounces across its 10U and 12U divisions.

A handful of leagues move to size 4 at U8 rather than U9, so check your club's rules — that is the one genuine source of ambiguity here, and it is settled by asking rather than by reading.

Choose size 3 if…

• Your kid is in U6, U7 or U8 and nobody has told you otherwise.
• They are eight and playing in a U8 division rather than U9.
• You want one ball to last several seasons and they are just starting — size 3 covers three years. See the size 3 picks.

Choose size 4 if…

• Your kid is in U9, U10, U11 or U12.
• They are turning nine this season and will be playing U9 matches with a size 4.
• Your league has confirmed it moves to size 4 at U8.
• You want the longest-lived single purchase — size 4 covers four years. See the size 4 picks.

Why the sizes exist at all

Worth understanding, because it is not bureaucracy and it changes how you think about 'just using the bigger one'.

A ball that is too heavy for a player produces two problems. They cannot strike it cleanly, so they learn to toe-poke it instead of striking properly — a habit that takes years to unlearn. And repeatedly kicking a disproportionately heavy ball loads a growing leg more than it needs to be loaded.

A ball that is too small has the opposite issue: it lets a player get away with sloppy contact, because there is more margin for error in where the foot meets the ball.

So the size bands are a development tool. Using the right one is not about rule-following.

What the transition actually feels like

Going from size 3 to size 4 is a real step and it lands at the same time as the format changing from 4v4 to 7v7 with a goalkeeper on a pitch roughly double the length. So a lot changes at once at U9.

For a few weeks, expect shorter passes, less clean striking and some frustration. It resolves with playing time. What does not help is sending them back to the size 3 — the adjustment is the point.

Should you practice with a size 4 before U9?

Yes, in the last few months of U8, and this is genuinely the most useful thing on this page. A size 4 ball in the yard through the spring before they move up means the transition happens at home rather than in their first competitive game.

Two caveats. Their games are still size 3 until they move up, so the size 3 stays in the gear bag. And do not do it a year early — a seven-year-old on a size 4 is back in the toe-poke territory the sizes exist to avoid.

The practical answer for families with two kids

If you have a U7 and a U10, you need both sizes — there is no useful compromise and a size 4 in a seven-year-old's yard will get used by the seven-year-old.

Buying the same model in both sizes is worth doing for a small practical reason: the adidas Starlancer family runs in sizes 3, 4 and 5, so both balls behave similarly and neither kid thinks theirs is the worse one. That sounds trivial and is not, in a house with siblings.

What comes after size 4

Size 5, at U13, and that is the last change. It is a bigger jump than this one — up to 28 inches and 16 ounces, arriving alongside 11v11 on a full pitch. See size 4 vs size 5 and the U13+ level page.