Age Calculator

Calculate exact age in years, months, days, hours and minutes.

Date of Birth
Select date
Calculate age on date (optional)
July 4, 2026

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How it works

Age is computed using a borrow-carry algorithm rather than naive millisecond subtraction, which gives correct months and days across leap years and varying month lengths. Years subtract directly; if the current month is before the birth month, one year is borrowed. The same borrow logic applies between months and days, using the actual length of the previous month. The next-birthday countdown uses Math.floor on full-day differences to stay correct across daylight-saving boundaries.


              // Borrow-carry per year-month-day:
// if days < 0: borrow 1 month (use prev month length)
// if months < 0: borrow 1 year (12 months)

Common use cases

  • Verifying age for legal requirements (driving license, voting registration).
  • Calculating exact age in years, months, and days for a birthday card or speech.
  • Counting down days until a milestone birthday or anniversary.

See also: BMI Calculator .

Frequently asked questions

Why does the result differ slightly from other age calculators?

Some calculators use 30-day months or 365-day years (rough averaging). This tool uses real calendar arithmetic with leap years and actual month lengths, so it matches how legal and medical systems compute age.

What if my birthday is February 29?

On non-leap years, the calculator treats February 28 as your birthday observance for the countdown. Your age increments correctly each year — leap-day people are not perpetually one-fourth of their stated age.

Does timezone matter?

The calculator uses your browser's local timezone for "today." Birthdays are stored as date-only (no time component), so as long as you and the date are in the same calendar day locally, the result is correct.

Embed this tool

Add this free age calculator to your own website or blog — copy the code below and paste it into your page HTML. No signup, no API key. 

<iframe src="https://otoolrun.com/embed/age-calculator/" width="100%" height="560" style="border:0;border-radius:12px" loading="lazy" title="Age Calculator"></iframe>
<p style="font-size:14px"><a href="https://otoolrun.com/tools/age-calculator/">Age Calculator by oToolRun</a></p>