How the age calculation works
This calculator measures age the way people naturally state it: in completed calendar years, months and days. It starts from the full years between the two dates, then counts the remaining whole months, then the leftover days. When a month has to be borrowed, it uses the real number of days in that specific month, so results stay accurate across leap years and months of different lengths. The totals (days, weeks, hours) are derived directly from the exact calendar difference, not from an approximate 30-day month.
Frequently asked questions
How does this age calculator work?
Enter your date of birth (or any start date) and an end date, which defaults to today. The tool counts full years, then remaining months, then remaining days, borrowing the correct number of days from each calendar month so leap years are handled exactly.
How is age calculated in years, months and days?
Age is measured in completed calendar periods. If the end day is earlier in the month than the birth day, one month is borrowed using the actual number of days in the previous month. If the end month is earlier than the birth month, one year is borrowed. This matches how people normally state their age.
Does the calculator handle leap years correctly?
Yes. Total days come from real calendar dates, so February 29 and every leap year are counted exactly. Someone born on February 29 sees their next birthday on February 28 or 29 depending on whether the upcoming year is a leap year.
Is my birth date sent anywhere?
No. All calculations run entirely in your browser with JavaScript. Nothing is uploaded, stored on a server, or tracked, and the tool works offline once the page has loaded.