How old am I? See your age in days, weeks, and months.

Completed years versus elapsed days

Calendar age counts birthdays already reached. We subtract the birth year from the current year, then subtract one more year if this year’s birthday is still ahead. Someone born on 14 June 1994 is 31 on 13 June 2026 and 32 on 14 June 2026. Dividing elapsed days by 365 is not the same calculation: leap years add days and birthdays follow calendar dates.

Elapsed days are the difference between the two local calendar dates, excluding the starting date. For example, 1 January to 8 January is 7 days, or 1 week. A person born today has 0 elapsed days. We compare date components using UTC day markers so a 23-hour or 25-hour daylight-saving day still counts as one calendar day.

The reference date is today in your browser’s time zone. Results update after the page loads and at local midnight. We do not ask for a birth time: these are calendar-day results, not an exact count of hours or seconds since birth.

Why weeks and months look different

A week is always 7 days, so weeks equal elapsed days divided by 7. The display can include a fraction rather than counting only finished weeks. Months vary from 28 to 31 days. Our mean-month figure divides days by 30.436875 (365.2425 ÷ 12); it is not the number of completed calendar months.

For a 366-day interval, the results are about 52.3 weeks and 12.0 mean months. Rounding can hide a small fraction, so use the whole-day total when checking an exact duration. The Gregorian calendar’s 400-year cycle contains 97 leap years, which gives the 365.2425-day mean used for these conversions.

Leap-day birthdays and the next birthday

The countdown includes 0 when the birthday is today, then moves to the next year on the following day. For a 29 February birth date, this calculator uses 1 March in non-leap years and 29 February in leap years. For example, a person born on 29 February 2000 is shown as 24 on 28 February 2025 and 25 on 1 March 2025.

This is a stated calculation convention. Do not use it to decide legal eligibility, benefits, or an official age threshold; those rules can differ. Invalid dates and future birth dates do not produce age results.

What does age on another planet mean?

Planetary age expresses the same elapsed time in different orbital units. We divide elapsed days by 365.2425, then by the planet’s approximate Earth-relative orbital period from NASA’s planetary ratio fact sheet. For 3,652.425 elapsed days (10 mean Earth years), the Mars conversion is 10 ÷ 1.88, or about 5.32 Mars years.

These are educational approximations using rounded tropical orbital ratios, not ephemeris calculations. They do not model where a planet was on your birth date, change how quickly your body ages, or predict lifespan. We do not infer population rankings or life expectancy from your birth date.

Sources, ownership, and corrections

The calculations and explanations on this page are maintained by Marko Blagotinšek, the operator of What Is My Age. The calculator runs in your browser and does not submit the selected birth date to our servers. See our privacy policy for hosting and analytics details.

• U.S. Naval Observatory: Gregorian leap-year rules — the calendar basis for mean-year and mean-month conversions.
• NASA: planetary fact sheet, ratios to Earth — approximate tropical orbital periods (table updated 18 March 2025).

Found a mismatch? Send the two calendar dates, expected result, and browser time zone to privacy@whatismyage.info. An invented example is enough; please do not send someone else’s personal birth date.