How to calculate age from date of birth
Forms and job applications often need your exact age in years, months and days. Here is the method, step by step.
Your age in whole years is easy: subtract your birth year and take one off if your birthday has not come yet this year. But forms, job applications and visa offices often need your exact age in years, months and days. Here is the method, including the tricky "borrowing" step and 29 February birthdays.
Step-by-step method
Write the date you are measuring to (today, or a closing date) on top, and your date of birth below it, as day, month and year. Subtract from right to left, starting with days.
- Days: subtract the birth day from the target day. If the result is negative, borrow one month: add the number of days in the month before the target month, and take 1 off the months.
- Months: subtract the birth month from the target month. If negative, borrow one year: add 12 and take 1 off the years.
- Years: subtract the birth year from the target year.
Worked example with borrowing
Date of birth: 28 November 1990. Age on 6 October 2026.
- Days: 6 − 28 = −22. Borrow a month: September (the month before October) has 30 days, so −22 + 30 = 8 days, and October becomes month 9.
- Months: 9 − 11 = −2. Borrow a year: −2 + 12 = 10 months, and 2026 becomes 2025.
- Years: 2025 − 1990 = 35 years.
Exact age: 35 years, 10 months and 8 days.
More examples
| Date of birth | Age on | Exact age | Total days |
|---|---|---|---|
| 15 March 1995 | 6 October 2026 | 31 years, 6 months, 21 days | 11,528 |
| 28 November 1990 | 6 October 2026 | 35 years, 10 months, 8 days | 13,096 |
| 29 February 2000 | 6 October 2026 | 26 years, 7 months, 7 days | 9,716 |
Birthdays on 29 February
In a non-leap year there is no 29 February. Many systems, and our calculator, treat the birthday as falling at the end of February, so a person born on 29 February 2000 completes a year on 28 February in common years. Some legal systems use 1 March instead. If a precise date matters for an official purpose, check the rule the office uses.
Age in months, weeks and days
- Months: years × 12 + months. 35 years and 10 months is 430 months.
- Days: count the actual days between the two dates, which includes leap days. Multiplying years by 365 will be a few days short.
- Weeks: total days ÷ 7.
Which date of birth to use
For official purposes in Pakistan, use the date on your CNIC, B-Form or Matric certificate. For government jobs, age is counted on the date in the advertisement, usually the closing date. See how government job age limits are counted.
Common mistakes
- Borrowing the days of the wrong month. Use the month before the target month.
- Subtracting years first and forgetting to adjust when the birthday has not yet come.
- Using 30 days for every month.
Get the answer instantly with the age calculator, or in Urdu with the Umar calculator.
Frequently asked questions
How do I calculate my exact age?
Subtract your date of birth from today's date in days, months and years, borrowing from the month or year when a figure goes negative.
Which month's days do I borrow?
The month before the target month. For an age on 6 October, borrow September's 30 days.
How is age calculated for a 29 February birthday?
In non-leap years, most systems treat 28 February as the birthday. Some use 1 March, so check the rule for official purposes.
How do I calculate age in days?
Count the actual days between your date of birth and the target date, including leap days. A date difference calculator does this exactly.
Which date of birth should I use for forms?
The one on your CNIC, B-Form or Matric certificate.