4 Month Old Baby: Milestones, Weight & Diaper Size
Rolling starts, so never leave your baby alone on a bed or changing table.
| Average weight | 6.4 – 7.0 kg |
| Diapers a day | 7–9 |
| Tape diaper size | S / M |
| Pants size | S |
Milestones this month
- Laughs out loud
- Reaches for and grabs toys
- May roll from tummy to back
Every baby grows at their own pace. If your baby was born early, use their corrected age. Talk to your paediatrician if you are worried.
Diapers this month
Most 4 month old babies fit tape diapers in size S / M or diaper pants in size S. Pants make changes quicker once your baby starts rolling and wriggling. Not sure? Use our diaper size chart.
Quick answers
What diaper size does a 4 month old baby wear?
Usually S / M in tape or S in pants. Always choose by weight.
How many diapers does a 4 month old baby use?
About 7–9 a day.