Baby age, week by week
20 Weeks Old — How Many Months?
A 20-week-old baby is 140 days old — about 4 months and 18 days.
This week
Reaching with one hand starts, and naps often reshuffle for a while.
The math
20 weeks = 140 days ≈ 4 months + 18 days
A month is longer than 4 weeks — on average 30.44 days — so you can't just divide by 4. The exact answer shifts a little with the calendar, so for the day-perfect number, use the calculator with your baby's real birthday.
Get the exact age →What babies do around week 20
At 20 weeks your baby is near the 5 Months mark. Around this age, many babies:
- Sits alone for a moment or two
- Checks out toys with mouth, hands, and eyes
- Deeply attached to their favorite people