How to use the Age Calculator
- Enter the date of birth.
- The 'Age as on' date starts at today. Change it to any later date to find the age on that day, for example the cut-off date in a form.
- Read the age in years, months and days, plus total months, total days and the days to the next birthday.
Formula used
Age is the difference between the two dates, counted in whole years first, then remaining months, then remaining days. Total days is the exact number of days between the dates.
Worked example
Here is the Age Calculator worked through with the example values shown above, so you can check each step by hand.
| Inputs | |
|---|---|
| Date of birth | 2000-01-01 |
| Result | |
| Your age | 26 years, 9 months, 29 days |
| Total months | 321 |
| Total days | 9,799 |
| Days to next birthday | 63 |
How age is calculated
The calculator counts whole years first, then the remaining whole months, then the remaining days. For a date of birth of 1 January 2000 and an 'as on' date of 30 October 2026, the age is 26 years, 9 months and 29 days. That is 321 months or 9,799 days in total, and the next birthday is 63 days away.
When the birth day does not exist in a month, such as 31 January plus one month, the month is counted as complete on the last day of the shorter month. This keeps the result consistent for people born on the 29th, 30th or 31st.
When you need an exact age on a specific date
Many applications state that age is counted 'as on' a particular date, such as the closing date of a job notification, the first day of an academic year or the date of an exam. Set the 'Age as on' field to that date to check eligibility rather than using today’s date.
Insurers sometimes use age at last birthday and sometimes age at nearest birthday, and the two can give different premiums. Check which one your policy uses and use the exact result here to confirm.
Leap years and total days
Total days include every leap day between the two dates, so the figure is exact. Someone born on 29 February has a birthday only in leap years, and the calculator treats the birthday in other years as falling on 1 March for the 'days to next birthday' figure. Your local rules for legal age on such dates may differ, so check the form’s instructions if it matters.
Frequently asked questions
How is age calculated from date of birth?
Subtract the date of birth from the target date year by year, then month by month, then day by day. This calculator does it for you and handles different month lengths and leap years.
How do I find my age on a particular date?
Enter your date of birth and change the 'Age as on' field to that date. The result shows your age on that exact day.
How many days old am I?
The 'Total days' result shows the exact number of days between your date of birth and the 'as on' date, including leap days.
How do I find the days until my next birthday?
It is shown automatically below the age. If your birthday is today, it shows 0.
Does the calculator work for a future date?
Yes. Enter a future 'as on' date to see how old someone will be then. The date must be after the date of birth.
Why might an official age differ from this result?
Some documents use a specific cut-off rule, such as age completed on 1 July or age at last birthday. Follow the rule stated by the authority, using this calculator’s exact figures to check.
This calculator gives estimates for information only. Actual figures from a bank, employer, tax authority or doctor may differ. It is not financial, tax, legal or medical advice.