- a guess is you expect an answer in English units and get an answer in metric units.
- another guess is you expect driving distance and your algorithm is providing straight line distance
- what happens if you use the built in routine in the Map component rather than using a distance calculation method using Blocks?
Post you relevant Blocks as Abraham suggests and someone can provide specific advice.
This link might be helpful Calculer la distance entre son domicile et un point donnée dans une textbox - #2 by SteveJG