How to choose diaper sizes

Choosing the right diaper size can make a big difference in comfort, leak protection, and sleep. The key thing to know is that diaper sizes are based on weight, not age, and every baby grows differently.

1. Use Weight as Your Guide

Check the weight range on the box. If your baby is near the top of the range, it’s usually time to move up a size.

Typical diaper sizes

• Newborn: up to ~10 lbs

• Size 1: 8–14 lbs

• Size 2: 12–18 lbs

• Size 3: 16–28 lbs

• Size 4: 22–37 lbs

• Size 5: 27+ lbs

• Size 6: 35+ lbs

2. Signs the Diaper Is Too Small

• Frequent leaks or blowouts

• Red marks on waist or thighs

• Tabs feel tight

• Diaper looks overfilled quickly

If you see these, try the next size up.

3. Signs the Diaper Is Too Big

• Gaps around the legs

• Waist feels loose

• Diaper sags

• Leaks even when not full

A good diaper should be snug but not tight.

4. Different Brands Fit Differently

Not all diapers are shaped the same. If one brand leaks, another might fit better even in the same size.

5. When in Doubt, Size Up

Sizing up often helps with leaks, especially overnight or during growth spurts.

6. Don’t Buy Too Many of One Size

Babies grow fast. Start with smaller packs until you know what fits best.

Choosing the right size keeps your baby comfortable — and makes life a lot easier for parents too.