Age Category Calculator
Start Date
End Date
Age
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Age Category
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School Entry Years (Ontario)
JK: September --
SK: September --
Grade 1: September --
How Age Categories Are Calculated
- Infant: 0 to 17 months old
- Toddler: 18 to 30 months old
- Preschool: 31 to 43 months old
- JK (Junior Kindergarten): 44 to 55 months old
- SK (Senior Kindergarten): 56 to 71 months old
- Aged Out (6+): 72 months and older
JK Eligibility in Ontario
In Ontario, children are eligible to start Junior Kindergarten (JK) in September of the year they turn 4 years old. For example, if a child turns 4 anytime in 2023 (even if their birthday is in December), they are eligible to start JK in September 2023.
This system allows children to start school as young as 3 years and 8 months, or as old as 4 years and 8 months when they begin JK in September.