Tretten is a village situated in Øyer Municipality within the Innlandet county of Norway. It is located in the southern part of the municipality along the Gudbrandsdalslågen river, specifically positioned on Losna lake.
The village lies in the Gudbrandsdal valley and is accessible via the European route E6 highway. It is situated approximately 25 kilometres north of the town of Lillehammer, while the municipal center of Tingberg is located about 5 kilometres to its southeast.