Born: Luton, 19th December 1986
Calvin signed a two-year contract at Spotland in July 2014, a deal which has since been extended by a further 12 months.
The 29-year-old started his career with hometown club Luton in 2004 and spent four seasons at Kenilworth Road, which included loan spells at Grimsby and Bristol City, before linking-up with Crystal Palace.
He was used mainly as a substitute during his time with The Eagles and went out on loan to Brighton, Millwall, Swindon and Leyton Orient, before joining Port Vale in July 2012.
After helping Vale to promotion to League One in 2012/13, Calvin spent the following season with Mansfield and York.
The forward has been a regular substitute during his time with Dale, but has contributed valuable goals from the bench, including injury-time winners against Bradford and Port Vale in the 2014/15 season.