Stahl was born in Munich but spent a large part of his life in Italy. He studied at the Munich Acadamy, under von Löfftz and Diez and in 1866 worked as an illustrator and painter in Berlin. He later went to England where he closely studied the Pre-Raphaelites. Stahl was the co-founder of Vereinigung der XI which had its first exhibition in 1892 at the Galerie Schulte in Berlin. He moved in 1904 to Florence, where he remained until 1913 and was much influenced by Botticelli. He returned then to Munich before finally settling in Rome. He was at one time an active member of the Munich Sezession.