Calculator Tools
Find an exact calendar age between a birth date and any comparison date, plus total elapsed days and the next birthday.
Input
Simple workflow
How to use Age Calculator
- 1Enter Date of birth.
- 2Set Age on date to today or another date on or after the birth date.
- 3Select Calculate age, then review exact age, total elapsed days and the next birthday.
Good to know
Frequently asked questions
Can I calculate my age on a past or future date?
Yes. Change Age on date to the date you want to compare with your birth date, then select Calculate age. The comparison date must not be before the birth date.
Why is calendar age different from total days divided by 365?
Years can contain 365 or 366 days, and months vary in length. The calculator counts complete calendar years, then months, then remaining days. Total elapsed days is a separate measure of the same interval.
How does the calculator handle a 29 February birthday?
When the anniversary year has no 29 February, this calculator uses 28 February for exact age and the next-birthday calculation. For example, 29 February 2000 to 28 February 2025 returns 25 years, 0 months and 0 days; the following birthday is 28 February 2026.
What does next birthday mean if Age on date is my birthday?
Next birthday always means the first anniversary after Age on date. If the comparison date is the birthday itself, the tool shows the following year's anniversary rather than zero days.
Does the result include my birth time?
No. The tool compares calendar dates, so it does not calculate hours or use a time of birth. The initial Age on date is today's date according to your device.
Practical guide
Read exact age, elapsed days and the next birthday
Age Calculator compares Date of birth with Age on date. The comparison date starts at today according to your device, but you can choose a past or future date on or after the birth date. Select Calculate age to see exact calendar age, total elapsed days and the next birthday after that comparison date.
Calendar years and months are counted first, followed by remaining days. This differs from dividing total days by 365, because years and months have different lengths. Total elapsed days is shown separately. The calculation uses dates only; birth times and hours are not included.
Worked example
Find age and the next birthday on a chosen date
- Start with
- Enter 15 May 2000 as Date of birth.
- Choose
- Set Age on date to 20 September 2026 and select Calculate age.
- You get
- The exact age is 26 years, 4 months and 5 days, with 9,624 total elapsed days. The next birthday is 15 May 2027, 237 days after the comparison date.
Tips for a useful result
- Age on date must be on or after Date of birth. Choosing the same date returns zero years, months and days.
- Next birthday means the first anniversary after Age on date. If the comparison date is the birthday itself, the result uses the following year's anniversary rather than zero days.
- For a 29 February birth date, this calculator uses 28 February as the anniversary in a non-leap year. When a date does not exist in a target month, the calendar calculation uses that month's last day.
- Changing either date clears the previous result. Select Calculate age to get the updated result. Reset clears the birth date and result, and returns Age on date to today. Copy result includes explicit labels for all four results.
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