On the bottom left corner of the main map, there is a scale bar varying along with the zoom level
Here the 5 segments of the scale bar are showing a length decreasing from 1041.12 Km to 30.00 Km according to the zoom level. Note that because a map is a projection of the earth, the precision of the distance is dependent on the latitude. Thus, the scale bar has to be considered as accurate in the middle of the main map.
Euratlas Periodis Expert is available either in English or in French or in German.