Well, I would say that all you can do is take a best guess approach because not only are there turns and curves to navigate but there are also hills and valleys to navigate so getting a totally accurate number is just about impossible. So the way that I do a best guesstimate is to take a 100-pixel brush tip and set the spacing to 100% Then just draw a line following the path and count how many dots are there and multiple that by 100. You could use say a 10-pixel tip or whatever is needed.