How to use it
- Enter your date of birth. The age appears immediately for today’s date.
- Change “Age on” to any past or future date to see how old you were, or will be, on that day.
- Read the breakdown: exact age, then the same time in months, weeks, days, hours, minutes and seconds, plus your next birthday and the age you turn.
- Tick “Compare with someone else” and enter a second date of birth to see who is older and by how much.
- Copy the summary or the link; the link carries the dates in its fragment (nothing is stored on a server).
Example
Someone born on Tuesday, 15 May 1990 is, on 19 October 2026, 36 years, 5 months and 4 days old. That is 437 months and 4 days, 1,900 weeks and 6 days, 13,306 days, 319,344 hours, 19,160,640 minutes or 1,149,638,400 seconds. The next birthday is Saturday, 15 May 2027, 208 days away, when they turn 37.
How the age is calculated
The calculator adds the largest number of whole months that fits between the two dates to the date of birth (clamping the day to the length of the target month, so 31 January + 1 month is 28 or 29 February) and counts the calendar days that remain. Whole months are then split into years and months.
age = whole years + whole months + remaining days
total days = days(to) − days(from) (counted on the calendar, not in milliseconds)Total days come from the difference of the two dates expressed as day numbers, which is why a 23-hour or 25-hour daylight-saving day cannot shift the result. Hours, minutes and seconds are derived from the whole days (24 × 60 × 60); the time of birth is not asked for, so the totals are exact to the day, not to the hour.
29 February birthdays
A leap-day birthday only exists every four years. The calculator counts the anniversary on 28 February in common years (the last day of the month) and on 29 February in leap years. Legal practice differs by country – England and Wales treat 1 March as the birthday for age limits, New Zealand and Taiwan use 28 February – so check your local rule if a legal age threshold matters.
Supported years run from 1583 (the first full year of the Gregorian calendar) to 9999. Dates before 1583 would need Julian-calendar rules and are rejected.
Sources: Gregorian calendar – leap-year rule and adoption, February 29 – legal birthday conventions by country, ISO 8601 date representation (YYYY-MM-DD).
Questions
- How many days old am I?
- Enter your date of birth and read the “In days” row: it is the number of calendar days from your birthday to today. Multiply by 24 for hours; the calculator shows the hours, minutes and seconds for you.
- Why does the months-and-days part change at the end of a month?
- Months have 28–31 days, so “one month after 31 January” has to land on the last day of February. The calculator always adds whole months first and counts the leftover days afterwards, which keeps the day count between 0 and 30 and matches how most age calculators and legal rules work.
- Can I calculate my age on a future date or at the time of an event?
- Yes. Set “Age on” to any date between 1583 and 9999 – a wedding, a retirement date or a historical event – and the panel shows the age on that day and the next birthday after it.
- Does the calculator know my time of birth?
- No. Results are exact to the calendar day; hours, minutes and seconds are whole days × 24, × 1,440 and × 86,400. For a span that includes the time of day use the Days Between Two Dates tool with its time fields.