PDF: Well, you can put random measures like "100 km from X to Y" on a map, but technically the whole world is like 10x10km size, and towns are a couple km one from another (look at the nr of steps on the compass...).
10x10 km - really?
I mean: in W1 and W2 it is even harder to tell, because the "regions" are smaller then what you mostly get in W3.
For W3 (and if it is really that much important), one could traverse White Orchard horizontally/vertically using the slow walk, take the time it takes (game time), and then use Geralt's speed to perhaps calculate - roughly - the distance(s).
The compass in W3 really just shows (if you must have this) one of several possible paths to get to your actual target. No in any way precise counting of steps here.
Still, I wonder in what sense all of this could be useful?
Anyway, good luck!
Edit:
For W3: look at the boats you can use. They might have about 6 m in lentth.
And now look at the harbour in Novigrad: how many boats might you need at any point to span the distance from point x to point x?
Multiplied with 6 you probably could get to the numbers you need.
Or, ask support :)!