Age Calculator
Calculating an age means expressing the span between two dates in calendar years, months, and days. It looks simple, but month lengths (28 to 31 days) and leap years make it easy to get wrong by hand; this calculator follows the calendar rules and gives an exact answer.
Enter your date of birth and you get your age in years, months, and days, plus your total age in days, weeks, and months. The calculator also tells you how many days are left until your next birthday and which day of the week you were born on. Change the calculation date to find your age on any past or future date — a start date at work, an exam application, or any age cut-off.
Formula
Years = calculation year − birth year (one less if the birthday has not come yet) Months and days = the remaining span, using real calendar month lengths Total days = the actual number of days between the two dates (leap years included)
The common mistake is treating age as the difference in years alone: if this year's birthday has not arrived yet, one year has to be subtracted. Someone born in November 1990, for example, is 35 in August 2026 — not 36.
How to Calculate
- Select your date of birth: day, month, and year.
- The calculation date defaults to today; pick a different date if you need one.
- Read your age in years, months, and days, along with your total days and weeks, in the results section.
- Check how many days are left until your next birthday and which day of the week you were born on.
Worked Examples
Age of someone born in 1990
Someone born on May 15, 1990 is 36 years, 3 months, and 2 days old as of August 17, 2026 — a total of 13,243 days, which is 1,891 weeks and 435 months. Their next birthday is 271 days away, and they were born on a Tuesday.
Your age: 36 years 3 months 2 days · Total days: 13,243 days · Total weeks: 1,891 weeks
A millennium baby
Someone born on the first day of 2000 is 26 years, 7 months, and 16 days old on August 17, 2026 — 9,725 days, or 1,389 weeks, in total. They were born on a Saturday, and their next birthday is 137 days away.
Your age: 26 years 7 months 16 days · Total days: 9,725 days · Total weeks: 1,389 weeks
Born on February 29
A baby born on February 29, 2024 is 2 years, 5 months, and 19 days old on August 17, 2026 (900 days, or 128 weeks). In years that are not leap years the birthday falls on the first day of March; the next one is 196 days away.
Your age: 2 years 5 months 19 days · Total days: 900 days · Total weeks: 128 weeks