it helps if you have access to a graphical resizing program, and yes, many map makers use a map that is 140 pixels per square. I use zoom a lot, so I use relatively huge maps. Figure the average character can move 30 feet per turn, dash up to 60 feet in total. If your map is going to be 5 feet per square, you need an average distance of 6 to 12 spaces (if they are running in a straight line or fleeing or chasing. So if you are running an open field chase scenario, mapped at 5 feet per square, and you want to use a tactical map, in detail, like with a drawn or purchased tileset, you need something like 50 X 50 Squares Scale (125' X 125') , for 4 turns of the fight. 30' - 60' feet per turn, maybe 4 turns or straight line dash. Something smaller, you need smaller. If you are going old school with a hand-drawn map of a town, you can get away with lines and arrows, to show where PCs are, as long as you keep your relative distances clearly marked. If you are just going for flavor, whatever you have that players can see clearly, that is the key then, go for clean labels on buildings, etc. Cover and concealment, elevations, potential barriers to movement or height changes, etc... relatively obvious.