Age calculator
Enter a date of birth to get an exact age today, or on any date you choose, down to the day.
Your age
36 years, 4 months, 14 days
13,285 days old on 29 October 2026
How to use it
- Enter the date of birth.
- Leave the second date blank for the age today, or enter a date to find the age on that day.
- Read the age in years, months and days, and the same age in weeks and days for forms that ask for it.
Worked example
Born 15 June 1990, age on 13 September 2026.
36 full years passed on 15 June 2026. From there, two full months pass on 15 August, and 13 September is 29 days later: 36 years, 2 months, 29 days, or 13,239 days. The next birthday is Tuesday, 15 June 2027, 275 days away.
How this is calculated
Years and months are counted the way people count birthdays: a year is added on each anniversary of the birth date, then whole months, then the remaining days. Total days is the plain difference between the two dates, and weeks are total days ÷ 7, rounded down. When the birth day of the month doesn't exist in the target month, the month ends on its last day, so someone born on 31 January turns one month old on 28 February, and a 29 February birthday counts as 28 February in years without one.
Years and months are counted the way people count birthdays: a year is added on each anniversary of the birth date, then whole months, then the remaining days.
When the birth day of the month doesn’t exist in the target month, the month is counted as ending on its last day, so someone born on 31 January turns one month old on 28 February (29 in a leap year).
Total days is the plain difference between the two dates. Weeks are total days ÷ 7, rounded down.
A 29 February birthday is treated as 28 February in years that don’t have one.
Rates, sources and limits
Last reviewed 13 Sep 2026 by the CalcRabbit team. Estimates only, not financial, tax or medical advice.
Frequently asked questions
How is age counted in months when the day doesn't exist?
The month ends on its last day. Born on 31 January, you turn one month old on 28 February and two months old on 31 March. Different calculators handle this differently, which is why they can disagree by a day or two.
What's my age if I was born on 29 February?
You age normally; the calculator counts your birthday as 28 February in non-leap years, which is what most official bodies do. Some countries use 1 March; the difference is one day.
Why do forms ask for age in months or weeks?
Paediatric records use months up to age two and weeks for newborns, and some insurance and immigration forms ask for age in days. The rows give all three so you don't have to convert.
Does the time zone matter?
Only at the edges. Dates are taken as calendar dates with no time, so an age only changes at midnight on the birthday itself.