How To Know What Tshirt Size for kids

Here’s a clear Youth vs Adult Small T-shirt comparison (typical US unisex/cotton tees like Gildan, Hanes, Bella+Canvas, etc.). I use Gildan for adult tee's, and Bella Canvas for Kids and Youth. Measurements are approximate averages and vary slightly by brand.Side-by-Side Comparison (Chest = full circumference; Length = shoulder to hem)

Size	Typical Age/Fit	Chest	Body Length	Notes
Youth S	6–8 years	28–30"	20–22"	Short & proportional for kids
Youth M	8–10 / 10–12 years	30–32"	22–24"	Common for elementary
Youth L	10–12 / 12–14 years	32–34"	23–25"	Often labeled size 10–14 or 12
Youth XL	12–14 / 14–16 years	34–36"	25–27"	Closest overlap with Adult S
Adult S	Adult / taller teens	34–36"	27–29"	Longer torso & sleeves

Key Differences

• Body length is the biggest gap. Adult Small is usually 3–5 inches longer than Youth XL (and even more than Youth L). This is why Adult S can look baggy or too long on many kids/tweens.

• Chest often overlaps at Youth XL  Adult S.

• Youth cuts are shorter overall, with narrower shoulders and shorter sleeves relative to the chest.

• Adult cuts have wider shoulders, longer sleeves, and more adult proportions.

Practical Advice (especially for a 10-year-old in size 12)

• Size 12 kids’ / Youth L is usually still the better fit for most 10-year-olds.

• Switch to Adult Small only if the child is taller (roughly 5'2"+), broader in the chest, or Youth XL feels short/tight.

• Always check the specific brand’s chart — Gildan tends to be boxier/wider; Bella+Canvas and Next Level run slimmer.

• Best method: Measure a well-fitting shirt the child already owns (chest laid flat × 2 for circumference, plus length) and compare.