How to Calculate Chronological Age Manually (With Examples)
Chronological date is the total number of time, days, and years that a person has lived since their date of birth. This is the easiest way to calculate how old someone is. Unlike biological age, chronological age doesn’t depend on health, lifestyle, or diet. In this blog, we will see how to calculate chronological age manually with examples.
What is Chronological Age?
It is the number of years from a person’s birth to a certain date or today. Chronological dates are indicated in days, months, and years. They are used in healthcare, forms, schools, insurance, fitness assessments, legal documentation, etc.
Manual Method to Calculate Chronological Age
Step 1: Birth Date
Write down your full date of birth (DoB) in the format Day/Month/Year.
Step 2: Current Date
Write down the reference date you’re calculating age for, or today’s date.
Step 3: Subtraction
Subtract the birth date from today’s date.
Simple Age Calculation Method
Calculating Age Example
Date of birth: 14 April 2001
Today’s date: 16 April 2025
| Component | Calculation | Result |
|---|---|---|
| Days | 16 – 14 | 2 days |
| Months | April – April | 0 months |
| Years | 2025 – 2001 | 24 years |
Final results: So, the chronological age is 24 years, 0 months, and 2 days.
Calculate Age With Month Borrowing Formula
Month Borrowing Example
Date of birth: 28 August 2001
Today’s date: 16 April 2025
Step 1 – Days:
Current day (16) – birth day (28) = 16 < 28 (not possible to calculate)
- Let’s borrow 1 month from April, which has a total of 30 days.
- April will be changed to March. For example, 30 + 16 = 46 days.
- Now, recall from step 1: 46 – 28 = 18 days.
Step 2 – Months:
As we borrowed 1 month earlier, April will become March.
- March (03) – August (08) = 3 < 8 (not possible)
- Let us borrow for 1 year. So 2025 will become 2024.
- Adding 12 months to the birth month = 12 + 3 = 15.
- Recalling from step 2: 15 – 08 = 7 months.
Step 3 – Years:
2024 – 2001 = 23 years.
Conclusion: The chronological age will be 23 years, 07 months, and 18 days.
Chronological Age Formula
The Formula
Chronological Age = Current Date – Date of Birth
Before using the formula:
We have to break down the date into days, months, and years, as given in the examples mentioned above. After calculating days, months, and years, we can apply the formula.
Important Notes:
- Keep in mind that February has 28 or 29 days (leap year).
- Always use an actual number of days in a month.
- Follow the hierarchy for subtraction: days first, then months, and then subtract years last.
- You can borrow if today’s day or month is less than the birth day or month.