I used to use Google Earth for this, but I think the Distance Measure app for iPhone is a lesser hassle and more convenient, especially when I’m on the go and don’t really have access to a laptop or desktop PC.
One feature that I always found useful on Google Earth was that you could track the distance of a certain place from another. This is pretty important in my line of work. To make things even more convenient, the Distance Measure app does more or less the same thing, but with a huge advantage: you can save it on your mobile device so you can get all the measuring done and over with even when you’re on the go.
This very simple app lets you measure the point-to-point distance between two or more waypoints on a map. It uses online maps so it needs an internet connection.
Tap and hold to set a new waypoint, tap the options icon be able to clear all waypoints and start over.