Age Calculator
Calculate exact age in years, months and days from a date of birth, on today's date or any other, with totals and the next birthday.
About the Age Calculator
Enter a date of birth and the calculator shows the exact age in completed years, months and days. The second date, Age at Date, starts as today's date in your own time zone, but you can change it to find someone's age on any day: the cut-off date on an exam or job application form, the start date of an insurance policy, or a date in the past.
The method is the one people use by hand. It first counts completed months, where a month is complete when the same day number comes round again, then counts the remaining days. When the birth day doesn't exist in a month, the last day of that month is used. So someone born on 31 January has completed one month on 28 February (29 in a leap year), and someone born on 29 February reaches each new year of age on 28 February in non-leap years. Leap years follow the Gregorian rules, including the century exception: 2000 was a leap year, 1900 was not.
Example: for a birth date of 15 May 1990, on 2 October 2026 the age is 36 years, 4 months and 17 days. That is 13,289 days or 1,898 complete weeks, and the next birthday, 15 May 2027, is 225 days away. If you are filling in a health form, the BMI Calculator works out body mass index for adults.
How to use the Age Calculator
- 1
Enter the date of birth
Use the Date of Birth picker or type the date.
- 2
Check the Age at Date
It is set to today. Change it to calculate the age on another date, such as an application deadline.
- 3
Read the result
Years, months and days appear at once, with total months, weeks, days and hours, and the date of the next birthday.
What it can do
Exact years, months and days
Counts completed calendar months and then the remaining days, with no negative or rounded values.
Age on any date
Change Age at Date to see how old someone was or will be on a particular day.
Totals
Total months, complete weeks, days, and hours (days × 24) between the two dates.
Next birthday
Shows the date of the next birthday and how many days away it is from the Age at Date, or a birthday message on the day itself.
Leap years and month ends
Handles 29 February and the 29th, 30th and 31st of the month with a consistent last-day-of-month rule.
Limitations
- Only dates are used, not the time of birth, so Total Hours is simply the number of days multiplied by 24.
- A 29 February birthday is treated as 28 February in non-leap years. Some laws and organisations use 1 March instead, so check the rule that applies if it matters legally.
- It uses the Gregorian calendar only. Birthdays based on other calendars, such as Hindu tithi dates, are not supported.
- The date of birth must be on or before the Age at Date.
Privacy
Both dates are processed in your browser and are not sent to FlexyPdf's servers.
Frequently asked questions
How is age calculated for someone born on 29 February?
In leap years the birthday is 29 February. In other years the calculator uses 28 February, the last day of the month, so the age increases by one year on 28 February and the next-birthday countdown points to that date. A note under the result reminds you of this rule.
Why does 31 January to 28 February count as one full month?
February has no 31st, so the last day of February stands in for it. Without that rule, someone born on the 31st would have no monthly anniversary at all in February, April, June, September or November.
How do I find my age on an exam or job cut-off date?
Enter your date of birth, then set Age at Date to the cut-off date given in the notice. The years, months and days shown are your age on that day.
Does my time zone affect the result?
Only in setting today's date: Age at Date starts as today in your own time zone. After that, the calculation uses calendar dates only, so daylight-saving changes and time zones do not shift the result.
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