2 - 3
FATMAP difficulty grade
This is the most direct route up Gaustatoppen (1) starting at the foot of Langefønn then heading straight up (insert switchbacks as needed) before (2) veering onto the route that is typically marked with yellow route markers for low-visibility days and then proceeding right up the ridge to the DNT cabin.
There are a couple steep sections that can be made more gentle by inserting some switchbacks.
If it is a hard day, the steeper and upper sections can require ski crampons.