Age Calculator
Find your exact age on any date, including total months, weeks and days, the weekday you were born and how long until your next birthday.
Result
Enter your values and select Calculate to see the result.
How to use this calculator
- Enter the date of birth.
- The “Age on date” defaults to today in your time zone; change it to find an age on any other date.
- Choose how 29 February birthdays should be counted in non-leap years.
Formula
The calculator counts whole calendar months forward from the date of birth until the next month would pass the reference date. Whole months are then split into years (12 months each), and the remaining days are counted exactly.
Total days is the exact number of days between the two dates, so leap days are included.
Worked example
Born 15 May 1990, age on 20 August 2024
From 15 May 1990 to 15 May 2024 is 34 years. 15 May to 15 August is 3 months, and 15 to 20 August is 5 days.
Age: 34 years, 3 months, 5 days, which is 12,516 days in total.
A 29 February birthday
Born 29 February 2000, age on 28 February 2001:
- “1 March” rule: 0 years, 11 months, 30 days — the first birthday falls on 1 March 2001.
- “28 February” rule: 1 year, 0 months, 0 days.
Assumptions and limitations
- Dates are calendar dates with no time of day or time zone, so the result does not depend on the hour you were born.
- The 29 February setting also applies when a birth day (such as the 31st) does not exist in a particular month.
- Legal definitions of when a leap-day birthday occurs vary by country; choose the rule that applies to you.
- Dates use the Gregorian calendar throughout.
Frequently asked questions
When does someone born on 29 February have a birthday in non-leap years?
Customs and laws differ. Some places treat 1 March as the legal birthday in common years and others use 28 February. This calculator lets you choose either rule.
Can I calculate an age on a past or future date?
Yes. Change the “Age on date” field to any date on or after the date of birth.
Why does my age in months not match years × 12?
Total months counts every completed month, including the months beyond your last birthday. For 34 years and 3 months the total is 411 months.