How this age calculator works
The calculator counts completed calendar years first, then the remaining calendar months and days from the last birthday to the comparison date.
Age today vs another date
Today mode uses your browser date. Selected date mode lets you calculate age on a past or future date, as long as the comparison date is on or after the birth date.
Leap-day birthday assumptions
February 29 birthdays are valid. The default treats Feb 29 birthdays as Feb 28 in non-leap years, with an advanced option to use Mar 1 instead.
What this calculator does not include
This calculator does not store personal data, verify identity, infer time of birth or provide legal, medical, school, pension or eligibility advice.
Key terms and assumptionsShort notes about calendar age, total days, leap-day birthdays, privacy and excluded advice.
- Calendar age
- Age is counted as completed calendar years, then remaining calendar months and days.
- Total days
- Total days is elapsed calendar days from the birth date to the comparison date. It is not inclusive day counting.
- Leap-day birthdays
- Feb 29 birthdays use Feb 28 in non-leap years by default, with an option to use Mar 1.
- Browser-only input
- The entered birth date is used in the browser for the calculation and is not stored by this tool.
- No eligibility advice
- The result does not determine legal, medical, school, pension or identity eligibility.
Related calculators and tools
Browse the Date & Time tools hub for related Date & Time tools.
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FAQs
How is age calculated?
Age is calculated by counting completed calendar years, then remaining months and days to the selected date.
Can I calculate age on a future date?
Yes. Use selected date mode, as long as the date is on or after the birth date.
Does the tool store my birth date?
No. The calculation runs in the browser and does not collect personal data.
How are Feb 29 birthdays handled?
The default is Feb 28 in non-leap years, with an advanced option to use Mar 1.
Why is total days different from the birthday count?
Total days is elapsed calendar days from birth date to the comparison date and does not add an extra inclusive day.
Does this provide legal age eligibility?
No. It is a general age calculator, not legal advice.
Does time of birth matter?
No. This version uses calendar dates only.