Age Calculator
Enter a date of birth – the age calculator shows the exact age in years, months and days, the total in days, weeks and months, and when the next birthday is. Leave the second date empty to use today – or set a test or cut-off date to use it as a chronological age calculator. Example: born 15 March 1990, the age on 21 October 2026 is 36 years, 7 months and 6 days (13,369 days).
Source: ISO 8601 – Date and time format (Gregorian calendar). Updated: .
How it is calculated
How the age is calculated
The age calculator counts from the date of birth to the chosen date (empty: today) in three steps:
- Full years up to the most recent birthday.
- Full months after that birthday – each up to the same day of the month.
- Remaining days from the last monthly anniversary to the chosen date.
Example: born 15 May 1990, reference date 27 September 2026. The last birthday was 15 May 2026 → 36 years. Up to 15 September 2026 add 4 full months, then 12 more days to 27 September. The age is 36 years, 4 months, 12 days – in total 13,284 days (1,897 weeks and 5 days) or 436 months and 12 days. The 37th birthday falls on Saturday, 15 May 2027, 230 days later.
The day of birth counts as day 0, and on the birthday itself the new year of age is complete: someone born on 10 March 2008 is 18 on 10 March 2026. Leap years are counted day by day, so the total in days is exact.
Age examples on 21 October 2026
| Date of birth | Exact age | Days alive | Next birthday |
|---|---|---|---|
| 1 June 1950 | 76 years, 4 months, 20 days | 27,901 | 1 June 2027 (turns 77) |
| 24 December 1985 | 40 years, 9 months, 27 days | 14,911 | 24 December 2026, in 64 days (turns 41) |
| 15 March 1990 | 36 years, 7 months, 6 days | 13,369 | 15 March 2027, in 145 days |
| 1 January 2000 | 26 years, 9 months, 20 days | 9,790 | 1 January 2027, in 72 days |
| 29 February 2008 | 18 years, 7 months, 22 days | 6,809 | 1 March 2027, in 131 days (turns 19) |
| 1 November 2010 | 15 years, 11 months, 20 days | 5,833 | 1 November 2026, in 11 days (turns 16) |
Quick rule for any year: in 2026 a person is 2026 minus the birth year once the birthday has passed, and one year less before it. Born in 1990: 36 after the birthday, 35 before; born in 2000: 26 or 25; born in 1980: 46 or 45.
Born on 29 February
In years without a leap day there is no 29 February. This calculator then counts the new year of age from 1 March – the day after the last day of February, which is also how German law counts the age of majority. Other rules exist: some countries and many people celebrate on 28 February. If you need the legal answer for a specific country, check the local rules.
Age calculator or time calculator?
The age calculator works with calendar dates only. For a time span with clock times (hours, minutes, daylight saving time) use the time calculator; for days between two dates, adding days to a date or business days use the date calculator.
Calculating age in Excel
With the date of birth in A2, =DATEDIF(A2,TODAY(),"Y") returns the full years, =DATEDIF(A2,TODAY(),"YM") the months after that and =DATEDIF(A2,TODAY(),"MD") the remaining days. =TODAY()-A2 gives the age in days. Details are in Microsoft’s reference for the DATEDIF function.
More date tools: count down to the big day with the countdown timer, convert pet years with the dog age calculator, or measure any span between two dates with the date calculator. Want your birth year in Roman numerals? Use the Roman numeral converter.
Frequently asked questions
What is a chronological age calculator?
Chronological age is the time that has passed since birth on a given date, written in years, months and days. Enter the date of birth and, under “Age at the date of”, the test or cut-off date. Born 3 January 2018, the chronological age on 15 May 2026 is 8 years, 4 months and 12 days.
How do I calculate my exact age?
Enter your date of birth. The calculator counts full years to your last birthday, then full months and the remaining days to today. Born 15 May 1990 gives 36 years, 4 months and 12 days on 27 September 2026.
How old am I in days?
“Age in days” shows the number of days from the date of birth to the chosen date, including leap days. On the day you are born you are 0 days old, the next day 1 day.
How old will I be on a specific date?
Enter that date as the second date – for example an exam, a trip or your retirement date. The result is your age on exactly that day.
When is my birthday if I was born on 29 February?
In leap years on 29 February. In other years this calculator counts the new year of age from 1 March; some people and some jurisdictions use 28 February instead.
How many days until my birthday?
“Next birthday” shows the date, the weekday and the number of days from today (or from the chosen date). If it is your birthday, it says “Today”.
How do I calculate age from date of birth?
Subtract the birth year from the current year, then take one year off if this year's birthday has not happened yet. Someone born on 20 October 1990 is 35 on 28 September 2026, not 36.
How old am I in months?
The calculator shows the total number of full months as well. Someone born on 15 March 2000 is exactly 26 years, or 312 months, old on 15 March 2026.
How do I calculate age at death?
Enter the date of birth and set the date of death as the second date (“Age at the date of”). The result is the age reached in years, months and days.
How old is someone born in 1990 in 2026?
36 after the birthday in 2026, 35 before it. Someone born on 15 March 1990 is 36 years, 7 months and 6 days old on 21 October 2026.
What day of the week was I born on?
The calculator shows it under “Day of the week you were born”, right below your age: enter your date of birth and you get, for example, “Tuesday, 05/15/1990”. It uses the Gregorian calendar and does not depend on today’s date.
Sources and legal basis
As of: · Editorial policy
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