ToolPilot
Age calculator
Enter your date of birth and an optional “as of” date (defaults to today). We show your age in years, months, and days, total days lived, the weekday you were born, and a countdown to your next birthday from that reference date.
Dates
Results
Choose your date of birth to see results.
How it works
We treat both inputs as calendar dates in your local time zone. Your age in years, months, and days is the difference between those two calendar dates using month-length rules (so day counts borrow from the previous month when needed). Total days lived is the number of midnights between those dates. The next-birthday countdown finds the next occurrence of your birth month and day on or after the “calculate age on” date; leap-day birthdays use February 28 in non-leap years.
FAQ
Why can my age in months and days look different from total days divided by 30?
Calendar months are not a fixed length. We show a true calendar difference (years, whole months, then remaining days), which will not always match a simple “days ÷ 30” estimate.
What happens if I was born on February 29?
In non-leap years we treat your annual birthday as February 28 for the “next birthday” countdown, which matches how many official documents and celebrations handle leap-day births.
Does changing “calculate age on” affect the countdown?
Yes. The next-birthday countdown is always measured from that reference date—useful for legal cutoffs, planning, or checking what your age was on a past date.
Is this suitable for official or legal use?
This page is for general planning and curiosity. Jurisdictions can define “age” or “birthday” differently (time zones, cutoffs). Confirm important dates with official sources.