Age calculator
Find completed years, months and days for a chosen date, with birth dates calculated in your browser without uploading them.
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Calculate age for the date you need
- Enter a date of birth in the age calculator, checking the year as well as the month and day.
- Leave the reference date empty for today, use the Today button, or choose another date on or after birth.
- For a 29 February birth, select whether the anniversary falls on 28 February or 1 March in common years.
- Read the completed years, remaining months and days, then compare them with the date-based totals.
- Check the birthday countdown and weekday of birth, then copy the result with its reference date.
Ways to use a calendar age
- Answer how old am I today without manually borrowing days between months.
- Work out age on a specific date for a family timeline.
- Find age in days for a personal milestone.
- Plan a celebration using the next birthday's date and countdown.
- Keep a copied age calculation together with the leap-day convention used.
Calendar age and birthday questions
What counts as a completed month?
The calculator finds the largest whole number of months that fits before the reference date. If the destination month is shorter, the anniversary is clamped to its final day.
What happens when someone is born on 31 January?
In 2026, one month after 31 January is 28 February. The age on 1 March is therefore zero years, one month and one day.
How does the leap-day setting affect age?
For birth on 29 February 2000, the age on 28 February 2026 is 26 years with the default rule. Choosing 1 March gives 25 years, 11 months and 30 days.
Are the hours an exact measure of time lived?
No birth time is entered. Total hours equal calendar days multiplied by 24, and minutes equal days multiplied by 1440. Clock changes are not included; total weeks count completed seven-day periods.
What if the selected date is a birthday?
The birthday date can be the reference date itself. The countdown is then zero, and the message confirms the birthday on that selected date rather than assuming today.
Can I enter a future date?
The reference date can be in the future to explore a later age. The birth date cannot be in the future, and the reference date must not precede birth.