This wiki article says that Erik Lehnsherr was born on January 30th 1930 but I don't know what this is based on!
Probably this article in The Vulture
Take Magneto, who is just 14 years old when we meet him during World War II in a First Class prologue. Since that sequence takes place in 1944, we know the character was born around the year 1930.
It's dated May 27, 2016. The revision to add his birth date was made on May 14, 2017. I can't figure out where The Vulture got it from, but the location came from X-men: First Class
Erik: My parents were from Dusseldorf