Age Calculator
Your exact age in years, months and days, and when your next birthday is.
Good to know. Leap years are why your age in days isn’t just your age times 365. We count them properly.
How it works
In plain words
Count whole years first, then whole calendar months, then the remaining days. That’s how people normally state an age.
The formula
years = full years since birth months = full months since the last birthday days = days since the last full month
Worked example
Someone born on 15 June 1990 is 35 years old on 15 March 2026: exactly 35 years, 9 months and 0 days, or 13,057 days.
Sources
- ISO 8601, Date and time format Calendar dates in the Gregorian calendar, and weeks that start on Monday.
Sources checked September 29, 2026. 7 automated tests check its answers on every change.
About the age calculator
Your age in years is easy until you need it exactly. Forms, visa applications, insurance quotes, school admissions and sports categories often need the precise age on a specific date, and doing it in your head across month ends is fiddly.
This calculator counts the way people do. First, whole years since your birth date. Then, whole calendar months since your last birthday. Then, the days left over. Because months have different lengths, "1 month" can be 28 to 31 days, which is why the days figure is counted from the last full month rather than by dividing.
It also gives your age as a total number of months, weeks and days, which is handy for babies and toddlers (and for celebrating your 10,000th day, which arrives at about 27 years and 4 months).
People born on 29 February are handled too. In years without a 29 February, we show their birthday on 28 February, which is the legal convention in many countries. Some places use 1 March instead.
The "age on" date defaults to today, but you can set it to any date, past or future, to find out how old someone was, or will be, on that day.
Questions people ask
How do I calculate my exact age?
Count the full years since your birth date, then the full months since your last birthday, then the remaining days. The calculator does this using the real calendar.
How old will I be on a future date?
Set "Age on" to that date. The calculator works for any date after the date of birth.
When do people born on 29 February celebrate?
In non-leap years, this calculator uses 28 February, as many countries do legally. Some use 1 March.
How many days old am I?
The "In days" line shows it. On their 30th birthday, someone has lived 10,957 or 10,958 days, depending on how many leap years they have seen.