Age Calculator
Work out exact age in years, months and days, total days lived and the countdown to the next birthday.
How to use the Age Calculator
- Pick your date of birth with the date picker, or type it as yyyy-mm-dd.
- Leave “Calculate age on” as today, or choose another date to find the age on that day.
- Read your age in years, months and days, the total days lived, and the countdown to the next birthday with its weekday.
- Use Copy age to copy a one-line summary.
Good to know
- Dates are treated as plain calendar dates in your local calendar. Nothing is converted through UTC, so the day never shifts because of your time zone.
- Months are whole calendar months counted from the birth date. If the birth day does not exist in a month (31 January + 1 month), the date is clamped to that month’s last day, then the remaining days are counted from there.
- A 29 February birthday is observed on 28 February in non-leap years. The next-birthday countdown uses the same rule.
- Total days is the exact number of calendar days between the two dates. Dates must be real (2021-02-30 is rejected) and the date of birth cannot be after the “age on” date.
Examples
- Standard case
- Born 15 May 1990, calculated on 20 August 2024: 34 years, 3 months, 5 days — 12,516 days in total.
- Leap-day birthday
- Born 29 February 2000, calculated on 1 March 2023: 23 years, 0 months, 1 day. In non-leap years the birthday falls on 28 February.
- Age on a past date
- Born 15 May 1990, “age on” 14 May 2010: 19 years, 11 months, 29 days — one day before the 20th birthday.
Frequently asked questions
Why might my age in months and days differ from another calculator?
Calculators disagree on how to count months when the birth day is 29, 30 or 31. This tool clamps to the end of shorter months and states that rule, so results are consistent and reproducible.
Is my date of birth stored or sent anywhere?
No. The calculation runs in your browser and the date is not saved or transmitted.
Does it work for dates in the past or future?
You can calculate age on any real date after the date of birth, including future dates, which is useful for questions like “how old will I be on 1 January 2035?”.
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