When Frederick Mentzer was born on 15 August 1808, in Washington Township, Franklin, Pennsylvania, United States, his father, David Mentzer, was 33 and his mother, Elizabeth Bonebrake, was 33. He married Dorothy Monn about 1829, in Franklin, Pennsylvania, United States. They were the parents of at least 6 sons and 2 daughters. He lived in Franklin Twp, Franklin, Pennsylvania, United States in 1880. He died on 2 March 1892, in Quincy Township, Franklin, Pennsylvania, United States, at the age of 83, and was buried in Franklin, Pennsylvania, United States.