There are three methods of measuring the distance between two points in Locus Map:
(1) Quickest way of measuring distance between any two points on the map screen.
(1) Method of easy measuring of the distance between your actual GPS position and any point on the map.
Both methods (1) and (2) are provided by the Add new route&Measure feature:
The feature displays additional controlling items to the main screen as is described in Route planning >>:
Route computing - useful for exact road measuring. Turn it on, add waypoints and Locus Map will compute the route between them smoothly along the roads. Always turn the computing function first before you want to compute route between two new waypoints, not vice versa!
Areas can be measured by the Add new route&Measure function too.