How to Determine Distance On a Map
A map and compass bearing can point you in the direction you wish to travel, but don’t forget to also calculate the length of your route. For that, you can use the distance ruler — or bar scale — in the map’s bottom margin.
1. Place one end of a piece of string on the map at your starting point.
2. Lay out the string so it rests on top of the route you plan to use, bending the string so it conforms to any twists and turns of your expected journey. Pinch the string where it touches the map symbol for your destination.
3. Stretch the string on the bar scale of the map and measure it to the point where you are pinching it. That’s the approximate length of your route.
The elevation change would have a minor affect on the overall distance.
As an example, a slope of one foot vertical to 5 feet horizontal would be a 20 percent slope. This is moderately steep slope for a walking surface. At this slope the distance measured on a map would be less than a 2% increase in the actual distance on the trail.
like the string idea !
Doesn’t take elevation changes into account.
Hmm. I never knew that