Current for 2026•As of: July 2026

Age Calculator calculate exact age.

Enter birth date and reference date – instantly get years, months, days and total days

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Age Calculator

Exact age in years, months and days – calculated calendar-accurately.

Please enter a date of birth and a reference date

Important note

These calculations are for non-binding information only and do not replace professional tax advice. All information without guarantee. Learn more

Sources & calculation basis

Our calculations are based on the following official sources (as of: July 2026):

How the age calculator determines your exact age

Calendar-accurate, leap years included

The age calculator calculates the exact age between a birth date and a freely selectable reference date – by default, today's date. The result is given in four formats: years, months, days (calendar-based) as well as the total number of days as an absolute value. The calendar calculation uses a borrow algorithm that accounts precisely for month and year boundaries – even with irregular month lengths such as February.

A frequently underestimated detail in age calculation is the handling of leap years. The year 2024 had 366 days (because of February 29), while 2026 has only 365. This means: someone born on January 1, 2000 was exactly 26 years old on January 1, 2026 – and had lived exactly 9,497 days. Our calculator adds these leap year days automatically.

The reference date can be freely chosen – for example for retirement, anniversaries, or insurance questions. In the insurance sector and for contracts, age is often calculated at the start or end of a contract. In inheritance law, a person's exact age at a specific reference date can be legally relevant. Age is also significant for sports clubs (age categories), schools (school enrollment), and medical studies (age groups).

For the curious: your 10,000th day of life falls on May 16, 2027 for a birthday on January 1, 2000. Your 25,000th day of life would be about 68 years and 5 months after your birthday. With our date calculator (shift mode), you can calculate exactly on which date your next big "life-day milestone" falls.

Use cases for the age calculator

When do you need an age calculator?

Personal milestone
10,000th day of life, 10,001st morning, or your next round birthday
Insurance & law
Determine age at contract start, inheritance, or retirement
Sports & age categories
Calculate reference-date age for youth, senior, or age categories
Medicine & research
Exact age for studies, check-ups, or vaccination schedules
School & daycare
Reference-date age for school enrollment (September 30) or daycare registration
Curiosity & trivia
How many days have you already lived? What is your life-day record?

Calculation examples

Age at reference date 01/01/2026

Age at reference date 01/01/2026
ItemAmount
Birth date01/01/2000
Reference date01/01/2026
Age26 years
Total days9,497

Leap year birthday

Leap year birthday
ItemAmount
Birth date02/29/2000
Reference date03/01/2026
Age26 years, 0 months, 0 days
NoteBorrow algorithm: Feb 2026 = 28 days

Frequently asked questions about the age calculator

Calendar calculation, leap years and special cases explained

The calculator uses a calendar-based borrow algorithm: it first calculates the difference in years, months and days separately. If the day difference becomes negative (e.g. birthday on the 31st of the month, current day on the 15th), one month is borrowed and filled with the days of the previous month. The same applies to months. The result is always exact, in the notation "X years, Y months, Z days".

In years without February 29 (non-leap years), the algorithm treats February 29 like February 28 for the month-borrow calculation. On March 1 of a non-leap year, a February 29 birthday therefore results in a remaining age of 0 days – the birthday anniversary is considered fully reached. On March 1, the corresponding age would thus be an exact whole number of years.

Total days indicate how many days in total have passed since the birth date – simply the difference in milliseconds divided by 86,400,000 (ms per day). This number accounts for all leap years precisely. The display in years/months/days is calendar-based and can differ slightly, since months have varying numbers of days.

Yes. The "reference date" field is freely selectable. By default, it is set to today's date. For example, you can enter the date of a future birthday to calculate how old you will be then, or a date in the past to determine a historical age. The "Reset reference date to today" button always takes you back to the current day.

Some reference values: 18 years = approx. 6,574 days (excluding leap years), the 10,000th day of life ≈ at 27 years 4–5 months, 65 years (retirement age) = approx. 23,741 days, 100 years = approx. 36,525 days. The exact number depends on the leap years within your lifespan. Our age calculator shows the exact total days based on your specific birth date.

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