A birth number is a calculable number that is defined by solely your date of birth. A birth number (1 to 9, 11, 22 and 33), significantly explains certain range of your personality traits and also helps you understand yourself better. Check below how to calculate your Birth number and see it for yourself, if the number connects with you. How is a Birth number calculated: Take your date of birth, say for instance: 11/16/1990 (mm/dd/yyyy) Add up the digits with each other until you break it down to either a single digit number or 11, 22 and 33. 1+1+1+6+1+9+9+0 =28 2+8 = 10 1+0 = 1 Hence, the birth number that you belong to is ‘one’.