Size 4 vs size 5 soccer ball

The short answer: size 4 through U12, size 5 from U13. AYSO's published standards put the size 4 at 25.0–26.5 inches and 12–14 ounces for the 10U and 12U divisions, and the size 5 at 26.5–28.0 inches and 14–16 ounces from 14U upward.

The most common mistake here is assuming a twelve-year-old has already moved up. They usually have not — U12 is still size 4, and buying a size 5 for a U12 means a ball they cannot use in a game.

Choose size 4 if…

• Your kid is in U9, U10, U11 or U12. Including U12 — this is the one people get wrong.
• They are twelve and playing 9v9 rather than 11v11.
• You want a ball for the rest of their time in the size 4 band. See the size 4 picks.

Choose size 5 if…

• Your kid is U13 or older, or moving up this season.
• They are playing 11v11 on a full-size pitch.
• You want the last ball you will ever buy for them — because it is. See the size 5 picks.

The weight difference is the real change

An inch and a half of circumference sounds minor. Up to four ounces of weight is not: at the top of each range, a size 5 is roughly a third heavier than a size 4.

For a thirteen-year-old that shows up in three specific ways. A driven ball travels shorter and dips sooner than they expect. Heading it is genuinely more of an impact. And a long pass needs noticeably more work through the ball.

All three resolve with playing time. None of them means anything is wrong.

Why this transition feels harder than the last one

Because more changes at once. At U9, the ball got bigger and the format went from 4v4 to 7v7. At U13, the ball gets bigger, the format goes to 11v11, and the pitch goes to full size — AYSO lists 13U and 14U fields at 100 to 130 yards long against 70 to 80 for 11U and 12U.

So a player is simultaneously dealing with a heavier ball, twice as many teammates, and a pitch nearly half as long again. Expect a rough few weeks. The U13+ level page covers the rest of what changes.

How to prepare for it

One genuinely useful thing: get a size 5 into the yard in the last few months of U12. Their matches stay size 4, but home practice on a size 5 means the strike adjustment happens somewhere low-stakes.

This is more worth doing than the equivalent at U9, because the weight jump is larger and the competitive environment they are moving into is more demanding. A cheap size 5 for the yard is a sensible purchase in the spring before they move up.

This is where ball quality starts mattering

Two reasons the size 5 purchase deserves more thought than any previous ball.

First, it is permanent. Every earlier ball was outgrown; this one is not, so a good ball has years to earn its price rather than months.

Second, the player can now tell the difference. A U13 who strikes a ball cleanly and repeatedly will notice inconsistency in how a machine-stitched rec ball flies, in a way a nine-year-old genuinely cannot. That is the crossover point where match-ball construction stops being marketing.

The caveat, though: a match ball's advantage is flight consistency, and consistency is exactly what a winter in a hedge destroys. Buy a match ball for matches and a cheap one for the yard.

One thing that does not change

Inflation. Check the pressure range printed next to the valve and inflate to the middle of it. A size 5 holds more air and so loses pressure more noticeably as it ages — check monthly. A properly inflated ball barely dents under firm thumb pressure.