How do I calculate my age from my date of birth?

Subtract your birth year from the current year. If your birthday has not happened yet this year, subtract one more year from that total. Then count the months and days separately using the same subtract-and-borrow method. This tool does all of that automatically. You just get the finished answer.

Can I calculate my age on a specific date?

Yes. Instead of leaving the calculate-as-of field on today, pick any date, past or future, and the tool works out your age as of that day. Use this for school enrollment cutoffs, immigration age requirements, or figuring out how old you will be on a future date like a wedding or retirement.

How does this handle leap years?

Leap years are built into the calendar math, not added as an afterthought. If someone's birthday is February 29, this tool treats it as February 28 in non-leap years for counting elapsed years, the same convention most legal and administrative systems use, while still calculating the exact day count correctly underneath.

What is chronological age?

Chronological age is the time that has passed since birth, measured in the calendar: years, months, and days. It is different from biological age, which estimates how old a body seems rather than how long a person has actually been alive. When a form or a doctor asks for your age, chronological age is what they mean.

How is Korean age different from international age?

Korean age starts at one, not zero, on the day someone is born, and everyone's age increases together on New Year's Day instead of on individual birthdays. Depending on birth month, that can put Korean age one or two years ahead of the international age most of the world uses. Toggle Also show Korean age to see both numbers at once.

How do I calculate age difference between two people?

Switch to the Age Difference tab, enter both birth dates, and the calculator returns the gap as years, months, and days, plus a flat day count if you need one number instead of three. It works the same way whether the gap is a few months or several decades.

How accurate is this online tool?

It is accurate to the day, using real calendar date math rather than a simplified days-divided-by-365 estimate. Leap years, varying month lengths, and the borrow-a-month logic are all handled correctly. The one thing it cannot account for is a wrong birth date typed in.

How do I calculate age in Excel?

Put the birth date in a cell, then wrap it in Excel's DATEDIF function with "Y", "YM", and "MD" as the unit arguments to pull out years, months, and days separately. The full formula is in the Excel section above. It is the same calendar-based approach this tool uses, just typed out manually.

Yes. Everything runs in your browser using JavaScript. Your birth date never leaves your device. There are no servers processing your information and no account required. You can disconnect from the internet after loading the page and the calculator still works.

Can I use this for my pet?

Yes. Click the Pet Age tab, choose dog or cat, and enter how many years old your pet is. The tool converts to human-equivalent age using the standard veterinary formula, not the old seven dog years equals one human year shortcut.

Wie alt ist jemand, geboren 2025? Altersrechner

Your date of birth

Date of birth

Calculate age as of

Also show Korean age

Results

Total days: 453
Total weeks: 64
Total months: 14
Total hours: 10,872
Seconds lived: 0

2025 age range (2026)

	Alter
Alter nach dem Geburtstag (frühestes Datum im Jahr)	1
Alter vor dem Geburtstag (spätestes Datum im Jahr)	0

Browse 2025 by month

january 2025 february 2025 march 2025 april 2025 may 2025 june 2025 july 2025 august 2025 september 2025 october 2025 november 2025 december 2025

Example dates in 2025

Geburtsdatum	Aktuelles Alter	Calculator
1. Januar 2025	1	Open
15. Juni 2025	1	Open
11. September 2025	1	Open
31. Dezember 2025	0	Open

All dates in 2025 (sample)

Date	Page
1. Januar 2025	january-1-2025
15. Januar 2025	january-15-2025
31. Januar 2025	january-31-2025
1. Februar 2025	february-1-2025
15. Februar 2025	february-15-2025
28. Februar 2025	february-28-2025
1. März 2025	march-1-2025
15. März 2025	march-15-2025
31. März 2025	march-31-2025
1. April 2025	april-1-2025
15. April 2025	april-15-2025
30. April 2025	april-30-2025
1. Mai 2025	may-1-2025
15. Mai 2025	may-15-2025
31. Mai 2025	may-31-2025
1. Juni 2025	june-1-2025
15. Juni 2025	june-15-2025
30. Juni 2025	june-30-2025
1. Juli 2025	july-1-2025
15. Juli 2025	july-15-2025
31. Juli 2025	july-31-2025
1. August 2025	august-1-2025
15. August 2025	august-15-2025
31. August 2025	august-31-2025
1. September 2025	september-1-2025
15. September 2025	september-15-2025
30. September 2025	september-30-2025
1. Oktober 2025	october-1-2025
15. Oktober 2025	october-15-2025
31. Oktober 2025	october-31-2025
1. November 2025	november-1-2025
15. November 2025	november-15-2025
30. November 2025	november-30-2025
1. Dezember 2025	december-1-2025
15. Dezember 2025	december-15-2025
31. Dezember 2025	december-31-2025

Altersmeilensteine

Alter	Jahr erreicht
1	2026
5	2030
10	2035
13	2038
16	2041

So wird berechnet

Das Kalenderalter zählt vollendete Geburtstage. Grob: Referenzjahr minus Geburtsjahr, minus 1 wenn der Geburtstag noch aussteht.
Genaues Alter = Jahre + Monate + Tage zwischen Geburts- und Referenzdatum, mit korrekter Monatslänge.

Age = Reference date − Birth date

Weeks ≈ total days ÷ 7. Hours = total days × 24. Minutes = total hours × 60 (exact for whole-day spans).

Nahe Geburtsjahre

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