How to find chronological age?Step by step guide and examples
How to find chronological age?Step by Step Guide and Examples
When conducting a psychological test or speech therapy evaluation, the first requirement is the person’s chronological age, as it forms the basis of accurate testing and diagnosis. If we calculate an incorrect value, it will lead to a wrong assessment and diagnosis. This age can be calculated manually by subtracting the date of birth from the current date using the format (yy/mm/dd). However, factors such as leap years and varying days in months can make manual calculation complex, which involves borrowing months and years. To avoid all these complex and time-consuming calculations, use our free chronological age calculator to get an accurate, instant result.
How to find chronological age?
Manually determining chronological age is a simple process. Subtract the date of birth from the current date by writing both in the year/month/day format. Start with days, then months, and finally years.i.e. (yy/mm/dd) – (yy/mm/dd).
| Year | Month | Day | |
| Date of Test | 2026 | 03 | 25 |
| Date of Birth | 1995 | 02 | 18 |
| age | 31 | 01 | 7 |
Steps to Calculate Age:
Write the current date (Today’s) in backward(Year, month, and day) format.
YYYY/MM/DD
2026/03/25
Write the date of birth in backward format, too.
Example:
YYYY/MM/DD
1995/02/18
Next, subtract the day of birth from the current day.
For example, 25 – 18 equals 7 days.
Then, subtract the birth month from the current month.
Example, 03 – 02 equals 1 month.
Finally, subtract the birth year from the current year.
For example, 2026 – 1995 equals 31 years.
If the number of days is more than 15, round the age up to the next month.
But if it is less than 15, months remain the same
Write the result as (Year, Month). i.e, (31,1).
Result:
So, your complete age is 31 years and 1 month old.
Rounding up ages:
Case 1
If the number of days is greater than 15, the age is rounded up to the next month.For Example:
10 years, 7 months, 24 days → 10 years, 8 months
Case 2
If the number of days is 15 or less, the age is not rounded up and remains the same. For Example:
10 years, 8 months, 6 days → 10 years, 8 months
Common Problems in calculation:
The most common problem is when the day of the current date is less than the day of the birth date, which results in a negative number. Here is how to solve this problem.
Step1:Days of current/test are smaller than days of birth date.
For example, if your child’s test date is February 2, 2026, and their birth date is November 24, 1995, you cannot subtract 24 from 2
YYYY /MM/DD
current date:- 2026/2/2
birth date:- 1995/11/24
Problems in days: 2 – 24 =?
Problem in months 2 -11:?
Rule of calculation:
– Subtract 1 from Months.
– Add 30/31 to the days of the test.
– Subtract 1 year from the years.
– Add 12 to the date of the test Months.
To determine age in this case, follow these simple steps:
Step 1: Subtract Days first and Borrow 1 Month(30 or 31 days) if needed
To subtract days when current days are less than birth days, get 1 Month borrowed that is equal to 31 days(January) from the months, so after borrowing, February becomes January, i.e., month 1
2026/1/33(2+31)
1995/11/24
Step 2: If the months are fewer, borrow one year(12 more months) if needed.
If the current month is less than the birth month (1 minus 11), borrow one year. This will add 12 months.
2025/13/33. I.e, 1+12 = 13
1995/11/24
Step3:
2025 13 33
– 1995 11 24
So,
30 2 9
(Y, M, D ) = 30, 2, 9. Here, 9 < 15, so we will not round up the age, and the month remains the same
Final result:
(30Y,2M)
Leap year and varying days of months
Normally, February has 28 days, but every 4 years it has 29, so your year has 366 days now. This also affects the calculation. Another problem is that some months have 31 days, others have 30, and feb has 29 or 28. In this situation, there is a rough formula to calculate age in days: age in days = (Years * 365 ) + (Months * 30) + Days.
Frequently asked questions(FAQs)
Conclusion
Chronological age, also called calendar age, is the total time a person has lived since birth. When used with other age measures, it helps track a person’s development. It is important in daily life because it answers the common question, “How old are you?” Psychologists and speech therapists use it every day. Calculating age by hand is easy, but due to the complex calculation, it becomes difficult to avoid errors and is time-consuming, so avoid all this and use our free calculator.