Age calculator
Enter a date of birth to see the age in years, months and days, the same time in months, weeks and days, and the days to the next birthday. The age is counted on today’s date unless you pick another day.
How it works
The calculator counts calendar days, not hours, so the time of day does not change the answer. It starts at the date of birth and adds whole months for as long as the result does not pass the day that you count to. The whole months give the years and the months, and the days after the last whole month give the days.
Months are counted from the day of the month of birth. A month that is too short for that day ends on its last day, so a person born on January 31 reaches one month on February 28. The same rule puts the birthday of a person born on February 29 on February 28 in the years that have no leap day.
The second box, “Age on,” starts as today. Change it to see the age on any other day.
A worked example
A person was born on Tuesday, May 15, 1990. On Sunday, November 1, 2026 the age is 36 years, 5 months and 17 days. That is 437 months and 17 days, or 1,902 weeks and 5 days, or 13,319 days. The next birthday is on Saturday, May 15, 2027, in 195 days.
For a person born on February 29, 2000 the age on the same day is 26 years, 8 months and 3 days. The next birthday is on Sunday, February 28, 2027, in 119 days, and it makes 27 years.
What it leaves out
The calculator does not use the hour of birth, so it cannot say how many hours old someone is. It does not convert to other calendars, and it does not know which age a law or a form asks for. A law or a form may count a February 29 birthday another way, and the office that asks for the age decides.
Questions
How do you calculate your exact age?
Count the whole years from the date of birth, then the whole months since the last birthday, then the days that are left. Born on May 15, 1990, a person is 36 years, 5 months and 17 days old on November 1, 2026.
How many days old am I?
Subtract the date of birth from the day you count to. A person born on May 15, 1990 is 13,319 days old on November 1, 2026, which is 1,902 weeks and 5 days.
How is a February 29 birthday counted?
In years without a leap day the calculator puts the birthday on February 28. Someone born on February 29, 2000 turns 27 on February 28, 2027. That is the rule of this page and not of a law, so ask the office that needs your age which day it counts.
Can I find an age on a past or a future date?
Yes. The second box holds the day to count to, and it starts as today. Change it to see the age on a day in the past, such as a date on a form, or on a day in the future, such as the day of an event.
How is the next birthday worked out?
It is the day and month of birth in the year after the last birthday. The calculator gives its weekday and the days that are left: from November 1, 2026 to May 15, 2027 is 195 days.
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