Fit Size Guide

A trusted collective of experts guiding every decision we make. From product development to everyday parent support, our approach is rooted in professional insight, evidence, and care — doctor-guided, never influencer-led.

DID YOU KNOW

Using the wrong nappy size is one of the biggest causes of leaks and blowouts?

We’ll help you find the perfect fit for your baby.

What we put on our babies matters

Baby Weight

Approx. Age

Type
New Born 0 1-3 kgs 0 months Nappy
Size 1 2-5 kgs 1-4 months Nappy
Size 2 3-6 kgs 2-6 months Nappy
Size 3 5.5-8 kgs 4-8 months Nappy
Size 4 7-12 kgs 6-12 months Nappy
Size 5 11-18 kgs 1-3 years Nappy
Size 6 15-18 kgs 2-3 years Pull-Up Nappy
Size 7 18-25 kgs 3 + years Pull-Up Nappy

The Golden Sizing Rule

Always upsize when your baby reaches the second half of the weight range. Example: Size 2 covers 3–6kg. If your baby is at 5kg, move to Size 3. A nappy too small for the weight range will leak. Not because it is faulty, because it is not engineered for that load. The nappy is performing exactly as designed. It simply needs to be the right size. When in doubt: size up. Always.

Signs it’s time to size UP

  • You’re getting frequent leaks or blowouts
  • The tabs are stretching or don’t reach comfortably
  • Red marks appear around the waist or thighs
  • The nappy feels tight or leaves indents
  • Baby seems uncomfortable or fussy in their nappy

Signs it’s time to size DOWN

  • Gaps around the legs or waist
  • Nappy looks bulky or saggy, even when dry
  • Leaks happening despite the nappy not being full
  • Tabs overlap too far across the front
  • Nappy shifts or moves around easily

HELPFUL TIP

A good fit should be snug (not tight), sit just under the belly button, and have no gaps around the legs.

Still have sizing questions?

Our team is here to help. Email us any time at support@econappii.com

Email Us