How to work out the age group
US Soccer registers players by birth year. A season runs from August to July and takes the year it ends in, so for the 2026-27 season every player born in 2016 is U11, whatever month their birthday falls in.
Grade does not matter. Two classmates born in different years can play in different age groups.
Ball sizes
A size 5 ball is the full-size match ball: the Laws of the Game set it at 68 to 70 cm (27 to 28 inches) around and 410 to 450 grams. Sizes 4 and 3 are smaller and lighter versions for younger players, and the size is printed on the ball.
Leagues and tournaments set their own rules, and some move from size 3 to size 4 or size 4 to size 5 a year earlier or later. If your league says otherwise, follow your league.
Questions
What size soccer ball does a 10 year old use?
Usually a size 4. A 10 year old is in U10 or U11 depending on birth year, and both play with a size 4 in most leagues.
When do players switch to a size 5 ball?
At U13 in most US leagues.
Why is my child in a different age group than their age?
Because age groups go by birth year and the season end year, not by birthday. Enter the birth year above to see the group.
Is my data stored?
No. The math runs in your browser and nothing you type is sent anywhere or put in analytics.
Sources
Formulas and rules checked against these sources on October 28, 2026. Leagues and associations change their rules, so when your league's rulebook differs, follow your league.