Al Sim was born in Michigan and lived there till he was six. He spent the rest of his childhood and early adulthood in Pennsylvania, with the exception of eleven months on Wake Island in the North Pacific. He graduated magna cum laude from New York University with a degree in economics.

During and after college, Sim has lived in Manhattan and Brooklyn, in central Massachusetts and on Cape Cod, and in New Mexico, Virginia, and Arizona. He has worked in restaurants, in factories and warehouses, on construction sites, and on Wall Street. He is currently employed in the software industry. He is married and has two children.