Math & Everyday
Age Calculator
Enter a date of birth and a target date to calculate exact age in years, months, and days, along with the total days, weeks, and months elapsed.
Quick answer: Exact age counts whole years, then remaining months, then leftover days — accounting for leap years and differing month lengths.
Counts whole years, then remaining months and days, accounting for differing month lengths and leap years. Set the second date to any day to find age in the past or future.
How it works
1. Set the two dates
Enter your date of birth and the date you want to measure to — usually today. The calculator treats both as calendar dates so it can account for the exact number of days between them. Any start-and-end date pair works, not just birthdays.
2. Count years, months, and days
The tool subtracts the dates and breaks the gap into full years, then remaining months, then leftover days. Because months have different lengths, simple subtraction is not enough — the calculation borrows across month boundaries correctly. Leap years are handled automatically.
3. See the full breakdown
Beyond years, the calculator can show your age in total months, weeks, days, or even hours. This is useful for milestones, eligibility dates, and countdowns. Every figure derives from precise calendar math rather than rough averages.
Frequently asked questions
How is exact age calculated?
The calculator counts whole years from the birth date, then the remaining whole months, then leftover days — accounting for differing month lengths and leap years.
Can I calculate age at a future or past date?
Yes — set the 'age at' date to any date to find how old someone was or will be on that day.
Does it handle leap years?
Yes. It uses real calendar dates, so February 29 and varying month lengths are handled correctly.