Age Calculator
Work out an exact age in years, months and days, plus total days lived and time until the next birthday.
Privacy: This tool runs entirely in your browser. Your data never leaves your device and is never uploaded to any server.
Age
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Pick a date of birth. The date must be in the past.
How to use this age calculator
- Enter the date of birth.
- Leave the second date as today, or set it to any later date.
- Every figure updates immediately.
- Nothing is saved or uploaded.
What each figure means
| Figure | What it counts |
|---|---|
| Years, months, days | Complete periods, counted the way a person would |
| Total months | Every whole month since birth |
| Total weeks | Total days divided by seven, rounded down |
| Total days | Every day lived, including leap days |
| Total hours | Total days multiplied by 24 |
| Next birthday | Days remaining, and the date it falls on |
Why ages are counted in parts
Months are not a fixed length, so there is no single number of days that equals one month. Dividing total days by 30.44 gives a plausible average and an answer that disagrees with the calendar.
Counting complete years and months first, then the remaining days, is what a hospital record, a passport form or a birthday expects.
Where an exact age matters
- Forms that ask for age on a specific date rather than today.
- Medical and paediatric records, where ages are given in months for young children.
- Insurance and pension calculations that depend on an exact age at a date.
- Working out elapsed service, tenancy or warranty periods from two dates.
Frequently asked questions
How is the age calculated?
By counting whole years, then whole months, then the leftover days — the way you would work it out by hand rather than by dividing a number of days.
Why is the total in months not years × 12?
Because it includes the extra months of the current year. Total months counts everything since birth.
Can I calculate an age at a different date?
Yes. Change the second date to any point after the birth date, which is useful for records and forms.
How are leap years handled?
By the calendar itself. 29 February exists in leap years, and in ordinary years that birthday rolls to 1 March.
What if the birth date is 29 February?
Nothing breaks. The countdown targets the next 29 February, or the day after in a non-leap year.
Is my date of birth stored?
No. Nothing is sent to a server and nothing is kept between visits — closing the tab clears it.
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