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Age Calculator🔒 100% local
Calculate exact age from birthdate. Privacy-first, no server uploads, no tracking.
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Turns a birth date into an exact age: whole years, the leftover months, the leftover days, and running totals in months and days. You type the date, press Process, and the subtraction runs in the page against the clock on your own device, so the date you enter is never transmitted anywhere.
How to use it
- Type the birth date into the box in YYYY-MM-DD form, for example 1990-05-15.
- Press Process. Three lines appear below: the age, the total months and the total days.
- Use Copy Output to lift all three lines at once, or Clear to empty both boxes.
Worked example
1990-05-15becomesAge: 36 years, 4 months, 12 days
Total months: 436
Total days: 13284The real output for a run on 27 September 2026. The comparison is always against the current date on your device, so the figures advance as the calendar does.
2000-02-29becomesAge: 26 years, 6 months, 29 days
Total months: 318
Total days: 9707A leap-day birth date, from the same run. The day count comes from the month-borrowing rule in the code rather than a February 28 or March 1 anniversary, so other age calculators can disagree by a day or two here.
When to use it
- Filling in an age field that wants the exact split of years, months and days rather than a rounded number.
- Working out how many days old someone is for a countdown, a milestone post or an anniversary.
- Checking the age a person reaches on a signup date when a category or programme has an age condition.
What it does not do
- There is no as-of date to enter. The birth date is compared with today on your device, so the same input gives a different answer tomorrow.
- Only dates JavaScript can parse are accepted: 15/05/1990 and 19900515 are rejected, while 1990-05-15 is the form that always works.
- A 29 February birth date is not special-cased. Entering 2000-02-29 on 27 September 2026 returns 26 years, 6 months, 29 days, which follows neither the 28 February nor the 1 March convention some registries use.
- It reports calendar age only. There is no time of day, no timezone handling and no age in hours or weeks.