The coat-of-arms is from modern times. They were granted on 19 December 1986. The arms show a logging hook, which in the area was used to haul the logs, cut in the surrounding forests. The logs were transported over the streams and lakes to the sawmills. The people use long poles with hooks to haul the logs. The colours of the arms are green and silver, because the name is derived from an old word describing a field (green) near a lake (silver).
Fet is located on the eastern side of Lake Øyeren and includes the point at which the River Glomma enters the lake. The inland river delta that has formed is the largest in Europe and reaches the opposite shore of the lake, across its short axis. Until 1985, logs floated down the river were brought onshore here before the river entered its delta, and were then transported onwards by rail. Today, many of Fet's floating buildings have been preserved and converted into a museum and cultural centre.