US: Size 4 to Europe Size 1
Cross-market children’s diapers, nappies, and training pants apparel conversion mapping Size 4 specifications into 1.

Analyzing Size Equivalence Across Markets
US: Size 4: Corresponds to a weight range of 10–16.8 (22–37 ) and an approximate age bracket of 12–24 .
Europe Size 1: Corresponds to a weight range of 2.5–4.5 (5–10 ) and an approximate age bracket of 0–1 .