Rælingen is a village and municipality in Akershus county, Norway. It is part of the traditional region of Romerike. The administrative centre of the municipality is the village of Fjerdingby. Rælingen was separated from the municipality of Fet on 1 July 1929.The name is first mentioned around 1400 ("i Ræling"). It is probably an old district name (the name of the church site is Fjerdingby). The meaning of the name is unknown.
The coat-of-arms is from modern times. They were granted on 30 April 1981. The arms show a yellow pitchfork on a green background. It is a symbol for the local agriculture. A large part of the municipality is lowland, which historically has mainly been used to produce hay. The pitchfork has three prongs representing the three rivers that run through the municipality: Nitelva, Leira, and Glomma.