Age Calculator

Enter your date of birth and the date you want to check. Use today's date to find your age now, or choose another date to see how old you were then or will be in the future.

For example, if you were born on 15 June 2000, you are 26 years, 3 months and 21 days old on 6 October 2026. If a form asks for your age in completed years, the answer is 26.

Your birthday makes a difference. Someone born on 15 December 2000 is still 25 on 6 October 2026. Sharing a birth year does not always mean sharing the same age.

Start by subtracting your birth year from the year you are checking. If your birthday is still ahead in that year, subtract 1 from the answer.

Completed years = reference year − birth year. Subtract 1 if the birthday has not arrived.

Next, count the full calendar months after those years, followed by the days left over. Use the original day of birth for each monthly milestone. If a month does not have that day, use its last day for that month.

Here is how the calculation works from 15 June 2000 to 6 October 2026:

The 3 months come after the 26 full years. They are not the total months you have lived. Counting from actual dates also takes account of any leap days along the way.

Why your birth year is not enough

Take a birth date of 15 December 2000. Subtracting 2000 from 2026 gives 26, but that is the age the person will turn during the year. On 6 October, their birthday has not arrived, so they are still 25. They turn 26 on 15 December.

Completed age is the number of full years you have lived. Running age refers to the year of life you are in. Once you turn 26, you have completed 26 years and started your 27th year.

If a form asks for completed years, enter 26 for either of the last two examples. Being in your 27th year does not make your completed age 27. Even at 26 years and 11 months, you should not round up. If the form asks for years, months and days, enter the full result.

An instruction such as “age as on 1 August” asks for your age on 1 August. Use that date even if you fill out the form later or the examination takes place in another month.

Someone born on 15 June 2000 is 25 on 14 June 2026, turns 26 on 15 June 2026 and turns 30 on 15 June 2030. You can use the same calculation for a past photograph, an upcoming birthday or an application cutoff.

Some applications also give an allowed range of birth dates. The government job age calculator explains how to check your date of birth against that range.

You can describe the same age in several ways. For a birth date of 15 June 2000 and a reference date of 6 October 2026:

To find completed months, multiply the years by 12 and add the extra full months. To turn a total day count into weeks, divide by seven and keep the remaining days. Avoid treating a month as four weeks: four weeks is 28 days, while most months are longer.

Dividing total days by 365 gives an approximate age in decimal years. It will not give the same breakdown as calendar years, months and days. Similarly, hours or seconds calculated from dates alone are conversions. To measure the exact time since birth, you also need the birth time, the time you are checking and the relevant time zones.

Some months do not have the day you need. There is no 31 February, for example. This calculator uses the last day of that month, then returns to the original day for later monthly milestones. One month after 31 January 2025 is 28 February, while two months after the original date is 31 March.

Different ways of handling month endings can produce different months-and-days results, even when the total days agree. If you compare two calculators, check which rule each one uses.

If you were born on 29 February, you still gain a year of age every year. In a non-leap year, a birthday calculation may use 28 February or 1 March. The leap year birthday calculator explains these choices and counts birthdays that fall on an actual 29 February separately. An official age check may have its own rule.