Losna is a lake which lies in the municipalities of Ringebu and Øyer in Innlandet county, Norway. Losna is a part of the Gudbrandsdalslågen river, which is in this region so broad and runs so slowly that this stretch is recognized as a lake. The 9.84 km2 lake has a length of 11 km and it lies at an elevation of 181 m above sea level and the maximum depth of the lake is 55 m below the surface. The European route E6 highway and the Dovrebanen railway line both run along the shores of the lake.