Baby Age Calculator
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Baby's age in weeks, months, and days from birth — designed for infants and toddlers, not year-based adult age.
Rates last reviewed: July 2026
Birth date
Baby age
19 weeks, 4 months, 16 days
138 total days · as of 2026-07-31
- Birth date
- 2026-03-15
Related calculators
Baby age in weeks and months
Parents and pediatricians often track infants by weeks and months rather than years. This calculator counts calendar time from birth date to any reference date and reports total weeks (floor of days ÷ 7), total months (years × 12 + months), and remaining days.
It differs from the general age calculator, which emphasizes years first. Milestone guides, vaccination schedules, and growth charts frequently use week or month bands during the first two years.
Example: born March 15, 2026, as of July 31, 2026 → 19 weeks, 4 months, 16 days (138 total days). Update the as-of date for well-child visit planning.
Official sources
Rates and formulas in this calculator reference the documentation below. Confirm current numbers on the source site before relying on them. Links do not imply endorsement by those organizations of Calcometry or this tool.
Common questions
Why weeks instead of years?
Infant development milestones are published by week and month during the first year. Years matter less until toddlerhood.
Is this different from the age calculator?
Yes. The general age calculator leads with years. This tool highlights weeks and total months for baby-focused tracking.
Does this replace pediatric guidance?
No. It is calendar math only. Follow your pediatrician for growth, feeding, and vaccination timing.