Date of birth is the date that you were born, and is found on various legal documents like birth certificate, marriage certificate and--when you die--death certificate. Your age is how long it has been since you were born, as of today.
- Skill level:
Subtract the year of birth from the current year. For example, if birth year was 1970 and current year is 2010, 2010 minus 1970 gives you an age of 40 years.
Compare the current month to the month of birth. If current month is before the month of birth, subtract one year from age. For example, if birth month was October 1970 and current month is May 2010, your age is only 39 because a full year hasn't passed until October 2010.
Compare the current day to day of birth if the current month is the same as the month of birth. If current day is before the day of birth, subtract one from age. For example, if date of birth is May 20, 1970 and the current date is May 5, 2010, your age is only 39 for another 15 days.