Open Google Maps on your phone or computer
Tap and hold (mobile) or right-click (desktop) on the starting point
Select “Measure distance”
Move the map to set the next point (mobile: tap; desktop: click)
Continue adding points to extend the path
View the total distance shown on the screen
Remove points (mobile: undo; desktop: backspace or remove last point)
Clear the measurement (mobile: tap the X; desktop: clear/delete option)