Should be on the railplanner app, when you add all your trips

But does not seem to work for all countries (probably certainly not those who do not deliver data to system or for manually added trips). The only ALT I know (and still use) is the old -style printed former Cooks/European TimeTable book. Distances usually do not change so an old one will also do. Some local railplanners may still also show PDF-tables for separate lines and these may-or may not-include the rounded KM-distances