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Age calculator

Calculate exact age in years, months and days from a date of birth.

Input
Output
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Age calculator
Paste a date of birth and this tool calculates the exact age as of today — or any reference date you choose — broken down into years, months and days. It also converts the same span into total days, weeks, hours and minutes, so you can answer both "how old" and "how many days old" from one input.
The date format option reads YYYY-MM-DD, DD.MM.YYYY or MM/DD/YYYY, and ISO dates (YYYY-MM-DD) are always accepted no matter which format is selected, since they are unambiguous. Paste one date of birth per line to calculate several ages at once — each line is evaluated independently, and a line that cannot be read as a date is reported next to the input rather than stopping the rest. Turn on "Show day of week born" to see the weekday of each birth date, and "Show next birthday" to see how many days remain until the next one and which birthday number it will be. Choose "Table" as the output format to line the results up in columns instead of full sentences.
Leap years are handled correctly throughout: a 29 February birth date compared against a non-leap reference year falls back to 28 February for the age calculation, and the day count always borrows from the actual length of the previous month, never a flat 30 days. The reference date defaults to today but can be set to any past or future date — useful for calculating age as of a specific event, deadline or legal cutoff.
Everything happens in your browser. Dates of birth are never uploaded or logged anywhere. When you are done, copy the result, download it as a .txt file, or send the output back to the input to run it through another tool.
FAQ
How is age calculated?
The tool compares the date of birth with the reference date (today by default) and works out the exact number of full years, months and days between them, correctly handling different month lengths and leap years.
What happens with a 29 February birthday?
In a year without 29 February, the birthday is treated as falling on 28 February for the purpose of age and next-birthday calculations, which is the common convention.
Can I calculate the age of several people at once?
Yes. Put one date of birth per line and each is calculated independently — an unreadable line is reported without affecting the others.
Can I calculate age as of a date other than today?
Yes. Set the reference date option to any date — past or future — and every age, total and next-birthday figure is calculated relative to it instead of today.
Are the dates of birth I enter uploaded anywhere?
No. The calculation runs entirely in your browser and nothing you type is sent to a server.