Real Name According to Birth Date

We can't. A person's name can not be revealed with numerology calculations on the person's date of birth.

The name is assigned by parents (usually) or changed by the holder (sometimes). The birth date is when a person is born. They are two separate events.

I'm uncertain what is meant by "real name", so I assume you mean the birth name. Information that some people don't know is that changing one's name does not erase the birth name's influence.

However, changing one's name can contribute to a person's numerology energy ambiance. Characteristics to Consider for Name Change talks about characteristics that may be considered.