How to Use the Online "Distance Calculator" First, always try to measure the migration distance on your map. Use a ruler and the scale bar shown on the map. Then go to the "Distance Calculator" to check your answer. As shown on the 3 examples below, the format for latitude and longitude must be inserted exactly as shown or the calculator does not work! Example #1: Monarch Butterfly Example #2: Bald Eagle Example #3: Loon