Diaper Size Guide: How to Choose the Right Size
Quick Answer
Size diapers by weight, not age: newborn (NB) fits roughly 2-5kg, then size 1 (3.5-6kg) through size 6 (16kg+). Always check the weight range printed on the pack, since ranges vary slightly by brand. Size up on red marks or repeated leaks; size down when there are gaps at the legs.
Key Takeaways
- Size by weight — ranges vary slightly by brand
- Size up on red marks or repeated leaks; size down on gaps
- One size up at night adds absorbency for heavy sleepers
Getting diaper size right prevents the two most common problems: leaks and red marks. This guide covers weight ranges, the signs that it is time to size up or down, and how fit interacts with overnight and pull-up products.
Weight-Based Sizing
- Newborn (NB) fits roughly 2-5kg; size 1 about 3.5-6kg; size 2 about 5-8kg; size 3 about 7-12kg; size 4 about 10-14kg; size 5 about 12-18kg; size 6 for 16kg+.
- Always check the weight range printed on the pack — brands vary slightly. Weight beats age as the sizing guide.
Signs You Need to Size Up or Down
Size up when: red marks on legs or waist, repeated leaks especially overnight, or the tabs barely reach the middle. Size down when: leg gaps
How long do babies wear newborn diapers?
Typically 3-6 weeks, until they reach about 4-5kg — varies by baby's growth.
How do I know when to size up?
Signs: red marks on legs/waist, repeated leaks, or the diaper no longer closes fully.
When should my baby switch from tape diapers to pull-ups?
Usually when they start standing, walking, or resist lying down for changes — often around 12-24 months.
References
- Pampers Official - About Pampers — 品牌官方 (accessed 2026-08-01)
- AAP HealthyChildren.org - Diaper Rash and Diaper Care — AAP (accessed 2026-08-01)
- Pampers Official - What's in a Pampers diaper (component materials) — 品牌官方 (accessed 2026-08-02)
- JP CIA (industry) - Baby diaper material: key components and their functions — 行业媒体 (accessed 2026-08-02)