Numerology's convention is specific about this: the soul urge calculation uses your full birth name, exactly as it appeared on your birth certificate, not a nickname, married name, or shortened version. The reasoning given is that the birth name is the "original" naming, before any of it was chosen or changed later in life.
From there, the method isolates every vowel — A, E, I, O, U, and Y when it functions as a vowel sound, depending on the school — converts each to a number using the standard Pythagorean chart, and adds them up.
The tool below walks through that conversion for you. What comes out the other end is a single digit (or a preserved master number), which the next section explains how to read.