Calculate your age today or on a specific date
Enter your date of birth and the date you want to check. GreenCalc shows completed years, remaining months and days, total days lived, and the next birthday relative to your chosen date. You can use a past date to check your age at an event, or a future date to plan a milestone.
Looking at an application deadline? Read how to calculate age on a cutoff date. If the result differs from another tool, our guide to leap years and month-end birthdays explains the conventions that can change an answer. Browse the Time & Date calculators for this topic.
How to use the age calculator
- Enter a complete Gregorian date of birth. Check the year as well as the month and day.
- Keep the calculation date as today, or choose another date.
- For a February 29 birthday, choose March 1 or February 28 for non-leap years.
- Select Calculate age. Read the calendar age and the total-day result separately.
What the results mean
Calendar age counts completed birthdays, then complete months and remaining days. Total days counts the days between the two dates, excluding the starting day. A baby born today therefore has an age of zero days. Weeks divide that total by seven, with any remaining days shown separately.
Hours, minutes and seconds are day-based equivalents: one day is treated as 24 hours. They are not a precise measurement from your time of birth. The calculator does not ask for a birth time or birthplace.
Examples you can check
| Date of birth | Calculate age on | Result |
|---|---|---|
| 2000-06-15 | 2026-06-14 | 25 years, 11 months, 30 days |
| 2000-06-15 | 2026-06-15 | 26 years, 0 months, 0 days |
| 2025-01-31 | 2025-02-28 | 0 years, 1 month, 0 days |
| 2004-02-29 | 2025-02-28 | 20 years, 11 months, 30 days with March 1 selected; 21 years with February 28 selected |
Our calculation convention
The tool first finds the most recent birthday on or before the calculation date. It then advances whole months from that birthday, keeping the day number where possible and using the last day of shorter months where necessary. The remaining date difference supplies the days. For example, January 31 to February 28 in 2025 counts as one month. Other calculators may use a different month-end convention.
February 29 handling is an explicit choice. In a leap year the anniversary remains February 29. In a non-leap year it follows the option you select. The same choice applies to completed age and the next-birthday countdown.
Dates, privacy and limits
Today is taken from your device’s local calendar. The date difference uses date-only arithmetic so a daylight saving transition does not add or remove a day. The tool accepts Gregorian dates from year 0001 through 9998; it does not convert Persian, Hijri or other calendar dates. Convert those dates before entering them.
Your date entries are processed inside the calculator’s browser frame. They are not added to a sharing URL or submitted by this tool. For eligibility decisions, use the cutoff date and birthday rule stated by the organization; an age result alone does not establish eligibility.
Frequently asked questions
Can I calculate my age on a future date?
Yes. Replace the calculation date with the future date you need. The next birthday is shown relative to that selected date.
Why does a February 29 birthday need a setting?
Non-leap years do not contain February 29. Choose February 28 or March 1 for the calculation. Use the rule required by an organization when checking a cutoff date.
Does this accept Persian calendar dates?
No. This tool uses Gregorian dates. Convert a Persian or other calendar date before entering it.
Is my date of birth sent to GreenCalc?
The calculator processes your dates inside its browser frame without submitting them.
Are the hours and seconds exact?
They are calendar-day equivalents. The tool does not use your birth time, birth timezone or daylight saving history.