Size Chart Best Practices for Kids Shopify Stores
Age + height + growth. Kids sizing has a different logic.
The 4 Age Bands
Newborn / Infant (0-12M). Sized by month + weight. Onesies sized by NB / 0-3M / 3-6M / 6-9M / 9-12M.
Toddler (12M-4Y). 12M, 18M, 2T, 3T, 4T. Some brands swap to numeric (2/3/4) at age 2.
Kid (4-12Y). Numeric (4, 5, 6, 7, 8, 10, 12) or XS/S/M/L kid sizes.
Youth/teen (12-16Y). Junior numeric (00-13) or smaller adult sizes.
What to Show
Age band + height range + weight range + key body measurements. Helps parents whose 4-year-old is the size of an average 6-year-old (very common).
Growth Allowance Notes
"Order 1 size up if buying 6+ months ahead" for non-fitted items. "Order true to current size" for fitted items (school uniforms, swimwear, dance, sports). Make these notes visible.
FAQs
Kids sizing different?
Age + height + growth.
Size up?
For non-fitted, often yes.
Kids-grade sizing
Tailor Size Guide ships kids chart templates with age + height + growth fields.