Scale bars provide a visual indication of distance and feature size on the map. A scale bar is a line or bar divided into parts. It is labeled with its ground length, usually in multiples of map units, such as tens of kilometers or hundreds of miles. Scale bars are associated with a map frame in a layout.

The scale bar should shorter than the map itself. The largest distance (represented by the overall length of the scale bar) should be a round number, for example 1,000, and the subdivisions distances should be 50%, 25%, or 20% of that length.

The whole point of most drawings is to accurately portray the size of real world features. So they have to do just that - whether they're printed out or just being viewed on a screen. Always having a scale bar on your title block means size is always easily understood by everyone. Every drawing must have one.

Scale bar. Magnification can be calculated using a scale bar. This is a line drawn near the photograph or drawing which has a label showing the actual length of the bar before being magnified. Working out magnification: Measure the scale bar image (beside drawing) in mm.