How to calculate age with the Age Calculator
- Enter the date of birth.
- Enter Calculate age as of (optional), or leave it empty for the browser's current calendar date.
- Click Calculate age.
- Review the result, then choose Copy result or Download result (.txt) if you need the text elsewhere.
What exact age in years, months, and days means
The main result counts whole calendar years, then whole months, then the remaining days between the two dates. Each month keeps its actual length, so the calendar breakdown does not use a fixed 30-day month.
Date of birth: 2000-01-01
Calculate age as of (optional): 2025-01-01
Exact age: 25 years, 0 months, 0 daysThe result also lists Total days lived, Total full weeks (remainder in days), Approximate total months (avg 30.436875 days/month), Day of the week born, Next birthday, and Days until next birthday. Approximate total months is rounded to two decimal places. The years, months, and days line remains the calendar breakdown.
How to calculate age as of a date
Use Date of birth for the starting date. Leave Calculate age as of (optional) blank to use the browser's current local calendar date, or enter a past or future date. The target date must be the same as or later than the date of birth.
If the target date comes before the date of birth, the calculator shows an error and hides the result. An invalid date of birth or target date does the same. Reset clears both date fields, the result, and the result actions. Changing either date also clears the current result.
What the next birthday calculation does
The birthday section finds the next occurrence of the birth month and day on or after the target date. It also shows the weekday on which the date of birth fell. For a February 29 date of birth, the next birthday uses March 1 in a non-leap year. That fallback affects the birthday date and countdown, not the exact age breakdown.
Copy or download the age result
Copy result puts the plain-text summary on the clipboard when copying is available. If copying is unavailable, the text remains available for manual selection. Download result (.txt) creates age-calculator-result.txt with the dates, age breakdown, date totals, weekday, and next-birthday details.
Where age calculations come up
For a school or event date, enter that date in Calculate age as of (optional) to see the calendar age on that day.
For a form or note, calculate the age for its specified date, then use Copy result to place the plain-text result on the clipboard.
To check an upcoming birthday, enter the birth date and leave the target date blank. The result includes the next-birthday date and countdown.
Choose the right health calculator
Use Health Calculators to choose among the site's health tools. Use BMI Calculator for height and weight inputs and a Body Mass Index result. Choose Body Fat Percentage Calculator for body measurements using the US Navy circumference method. Calorie Calculator uses measurements, age, sex, and activity level for BMR, maintenance calories, or a daily calorie target.
Frequently asked questions
How do I calculate my exact age from my date of birth?
Enter your date in Date of birth, leave Calculate age as of (optional) blank, and click Calculate age. The result gives calendar years, months, and days based on the browser's current local date.
Can I calculate age on a past or future date?
Enter that date in Calculate age as of (optional). It must be the same as or later than the date of birth.
How does the age calculator handle February 29 birthdays?
A February 29 date of birth uses March 1 for the next birthday in a non-leap year. The exact age breakdown is calculated separately from that fallback.
How are total weeks and months shown?
Total full weeks use groups of seven days, with a remainder in days. Approximate total months divides total days by 30.436875 and rounds the result to two decimal places.
Does the age calculator send my dates anywhere?
The date arithmetic runs in browser JavaScript. The calculator code contains no fetch, XMLHttpRequest, sendBeacon, or form post for the entered dates.