Lady Gaga, 27, returned to the top of Forbes' list of highest-earning celebrities under 30. <a href="http://www.forbes.com/sites/dorothypomerantz/2013/07/22/lady-gaga-tops-forbes-list-of-top-earning-celebrities-under-30/"target=external>Forbes (link)</a> estimates that she earned $80 million between June 2012 and June 2013.

Canadian Justin Bieber, 19, performs at TD Banknorth Garden on July 20, 2013 in Boston, Massachusetts. Bieber earned $58 million in the last year and ranked second, according to Forbes, with the help of a music tour, and stakes in starups Spotify, Tinychat and Enflick.

Taylor Swift, 23, performs at LP Field during the 2013 CMA Music Festival on June 6, 2013 in Nashville, Tenn. Swift, with $55 million in earnings, ranked number three in Forbes' list. She ranked as sixth most powerful celebrity, according to Forbes' list this year in that category.

Calvin Harris, 29, attends the Ivor Novello Awards 2013 at The Grosvenor House Hotel on May 16, 2013 in London, England. Harris is a Scottish DJ, singer, songwriter and record producer who earned $46 million in the last year, according to Forbes, making his first debut in Forbes' list at number four. He wrote and produced Rihanna's Grammy award-winning song "We Found Love."

Barbadian singer Rihanna performs on stage, on July 10, 2013 in Monaco. Rihanna, 25, earned $43 million in the last year and is the fifth highest earning celebrity under age 30, Forbes said.