Age in Months Calculator
Useful for pediatric milestones, subscription planning, financial projections, and more.
Defaults to now—change it to compare against any date.
Birth: 1/1/1990, 12:00:00 AM
Reference: 1/10/2026, 4:00:00 AM
Calendar age: 36 year(s), 0 month(s), 9 day(s)
Total whole months: 432 month(s)
Approximate months (decimal): 432.3012 month(s)
Approximate years: 36.0251 year(s)
Total days: 13158 day(s)
How to Use This Calculator
Provide birth/start time
Include date and time to ensure accuracy around monthly rollovers.
Set reference point
Use today or any comparison date (e.g., enrollment date, forecast date).
Review months + breakdown
Get total months plus exact years/months/days to plan budgets or milestone celebrations.
Formula
Calendar Months = Years × 12 + Remaining Months
Approx Months = (Reference − Birth) ÷ (30.4375 days)
Approx Years = Approx Months ÷ 12
Example: 2022-05-15 → 2025-11-09 = 3 years, 5 months, 25 days → 41 calendar months.
Month-Based Planning Ideas
- Track baby development with month-level milestones.
- Plan subscription renewals or promo periods in monthly increments.
- Calculate how many months remain on leases or service contracts.
- Translate product lifecycles or warranties into calendar months.
Frequently Asked Questions
How accurate are “approximate” months?
Approximate months use an average month length (30.4375 days). For exact counts, use the whole-month total provided.
Does it handle February and leap years?
Yes—the calendar difference respects varying month lengths and leap days.
What if I only need years and months?
The calculator already breaks the result into years, months, and days. Use Age in Years, Months, and Days for more detail.
Can I compare two events?
Absolutely—insert any start and end timestamps to see the months between them.