The estimated time for hiking is calculated using Tobler’s hiking function with default parameters (https://en.wikipedia.org/wiki/Tobler%27s_hiking_function). This means that speed on flat surfaces is estimated to be 5km/h and maximum speed of 6km/h is achieved when going downhill at 2.86 degrees.
The estimated time for ski tours is calculated using Naismith’s rule (https://en.wikipedia.org/wiki/Naismith%27s_rule):
Time (hours) = (horizontal distance) / 4000m + (vertical gain) / 400m
I.e. Ski touring on a flat surface is assumed to have 4km/h speed and every 400m of vertical gain cost extra 1 hour.
Any estimated time displayed in FATMAP is based only on geometrical properties of the surface, i.e. distances and gradient of the terrain. No surface properties (like bush, swamps, etc) or crossing of rivers, streams and fences, etc are taken into account.