How to Calculate Age From Date of Birth - Have you ever forgotten your father's age? What about a teacher that refuses to tell you her age, but tells you her birth date? This is how to find a person's age by using dates and simple math.
1. Find out the date the person was born.
2. Subtract that date from the current year. For example, if the birth year was 1998, subtract 1998 from 2013.
The result is their age. The difference from the previous example is 15. A person born in 1998 would be 15 in 2013.
More often, a person who does not reveal their age may reveal the year in which they were a certain age. For example, your teacher might let slip that he graduated from high school in 1980. From this, you can infer that he was about 18 years old in that year.
3. Subtract the given year from the current year, as before. In this example, 2013 minus 1980 equals 33.
4. Now, add that sum to the age given. In this case, add 33 to 18. The result, 51, is your teacher's age.
