🍼 Age in Months Calculator
Find your exact age in total months, plus remaining days — handy for baby milestones, developmental checkups, and forms that ask for age in months.
Your Dates
Your Result
How the Age in Months Calculator Works
This calculator converts the calendar difference between a birth date and a reference date into a single total-months figure, plus any leftover days — the format commonly requested for infant and toddler age (e.g. "18 months" instead of "1 year, 6 months").
Formula
Remaining Days = days left over after whole months are counted
Worked example: A baby born June 15, 2024, on December 15, 2025 is exactly 1 year and 6 months old — or 18 months — with 0 remaining days.
How to Use This Calculator
- Enter the date of birth.
- Leave "Calculate Age As Of" as today, or change it to any other date.
- Read the age in total months plus the leftover-days breakdown.
Frequently Asked Questions
Why calculate age in months instead of years?
Pediatric growth charts, vaccination schedules, and developmental milestones for infants and toddlers are typically tracked in months rather than years, since a lot changes in a baby's first 24 months.
How many months is 1.5 years?
1.5 years equals 18 months (1 year = 12 months, plus 0.5 years = 6 months).
Does this account for different month lengths?
Yes — the calculation uses calendar-aware date arithmetic, so months of 28 to 31 days are handled correctly rather than assuming a fixed 30-day month.