How to use it
- Type your Birth date: the day, month and year you were born.
- To see your age on another day, type that day in Age on this date. Leave it empty to count up to today.
- Read Exact age for the years, months and days, then the totals in Total months, Whole weeks, Total days and Total hours.
- Check Next birthday and the Milestones of life table for the dates of the milestones.
How the exact age is counted
The years are the complete years between the birth date and your last birthday before the date you choose. The months and days then count forward from that birthday, one calendar month at a time.
If the day of the month does not exist in the next month, the count stops at the last day of that month. So 31 January plus one month is 28 February, or 29 February in a leap year.
Years = year of the last birthday − year of birth
Months and days = calendar months and days counted forward from the last birthday
Total days = chosen date − birth date
Whole weeks = total days ÷ 7, rounded down
Total hours = total days × 24- Total months are the completed years times 12, plus the months that are left.
- Total hours count calendar days, because the time of birth is not asked. A birth later in the day can make the true figure a few hours lower.
Leap years and birthdays on 29 February
In the Gregorian calendar a year is a leap year when it is divisible by 4, except century years, which are leap years only when they are divisible by 400. So 2000 was a leap year, while 1900 and 2100 are not.
Someone born on 29 February has no birthday in most years. This calculator uses 1 March as the birthday in a year without 29 February. Some people celebrate on 28 February instead, and some legal systems use 1 March: the United Kingdom is one example.
The milestones table
The table lists eight milestones in date order, whether they have already passed or are still ahead: 10,000, 20,000, 25,000 and 30,000 days; 1 billion and 2 billion seconds; 1,000 months; and the birthday in the 75th year of life.
A second-based milestone is turned into whole days, rounded up: 1,000,000,000 seconds is 11,574.07 days, so the date is 11,575 days after birth. Because the time of birth is not asked, a birth before 20:00 brings both second-based dates one day earlier than the table shows.
What this calculator does not include
- The time of birth and time zones: every date is a calendar day.
- Calendars other than the Gregorian calendar.
- Age limits set by law or by an employer, such as a retirement or licence age. Those are set by the organisation that applies them.
Worked example: born 15 June 1990, age on 10 November 2026
The last birthday before 10 November 2026 is 15 June 2026, so the years are 2026 − 1990 = 36. Four months from 15 June reach 15 October 2026, and 26 more days reach 10 November: 36 years, 4 months, 26 days.
From 15 June 1990 to 15 June 2026 there are 36 × 365 days plus 9 leap days (29 February 1992 to 29 February 2024), which is 13,149 days. The 148 days from 15 June to 10 November make 13,297 days in all: 1,899 whole weeks with 4 days left over, and 319,128 hours. In months, 36 × 12 + 4 = 436.
The next birthday is 15 June 2027, which is 217 days after 10 November 2026.
| Output | Value |
|---|---|
| Exact age | 36 years, 4 months, 26 days |
| Total months | 436 |
| Whole weeks | 1,899 |
| Total days | 13,297 |
| Total hours | 319,128 |
| Next birthday | Tuesday, June 15, 2027 (in 217 days) |
Frequently asked questions
Does the calculator use the time of birth?
No. Only calendar dates are used, so every figure is a whole number of days. The totals in hours are days times 24, which can be a few hours different from the exact figure for your time of birth.
How is my age counted before my birthday has come this year?
The age counts from your last birthday. Until the birthday arrives in the year you choose, the years stay at the previous birthday, and the months and days continue from that earlier one.
How is the age of someone born on 29 February counted?
In a year without 29 February the birthday is taken to be 1 March, and in a leap year it is 29 February. Some people celebrate on 28 February, so their own count can differ.
Why can a milestone date be a day different from another calculator?
The seconds milestones are rounded up to whole days because the time of birth is not asked. If you were born before 20:00, both of them fall one day earlier than the table shows.
Can I see my age on a date in the past or in the future?
Yes. Type any date in Age on this date to see the age on that day. Leave the field empty to count up to today.
Is the date I enter sent to a server?
No. The calculation runs in your browser, and nothing you type is stored or sent to us.
Sources
Figures and text last checked on Tuesday, November 10, 2026.