Age Calculator: instructions, examples and limits

What it does

Counts completed calendar years, then separately calculates elapsed calendar days.

Use the age calculator for a completed calendar age and an explicit elapsed-day count between a birth date and a reference date.

How to use it

1. 1

   Enter the birth date and choose the reference date, defaulting to today on your device.

2. 2

   Read the completed years and the separate calendar-day result.

3. 3

   For official records, verify the date convention and time zone used by the responsible organisation.

How the result is produced

Counts completed calendar years, then separately calculates elapsed calendar days.

Important limits

Date-only calculations use the Gregorian calendar and UTC day boundaries, so daylight-saving changes do not alter day counts. Years 0001–9999. A 29 February birthday advances on 1 March in non-leap years.

Checks before sharing or relying on the result

• The calendar result is not a medical or legal determination.
• Dates are interpreted as calendar dates rather than hidden clock times.
• Leap days and month lengths are handled explicitly; a browser clock can still be set incorrectly.

Choosing the next step

Use a calendar-date tool when the question is about dates on a page, and a duration tool when elapsed clock time matters. For a deadline across time zones, convert the times explicitly before relying on a local-device result.