Scale Panel

The Scale Panel provides parameters that determine the size and position of items on the drawing paper.

Scale
These parameters control the drawing scale. This is a ratio that works like the scale on a map when 1 inch corresponds to 10 miles.
Units
This parameter defines the measurement units for the drawing. This is similar to deciding the kind of ruler to use for a project. The choice applies to all objects on a drawing. For example if you are drawing icons for use on computer screens, "points" (there are 72 points in an inch) would be the logical selection for the units.
Origin
Use these parameters to place the location (0,0), in Cartesian coordinates, anywhere on (or off) the drawing.
Axes
Use these parameters to select the direction of the Horizontal and Vertical axes.
Multiple Scales
A drawing may contain different scales for different layers. Use these two controls to manage drawings with multiple scales.

The scale of a drawing can be a confusing concept. If it is possible try to use a scale of 1:1. Before the use of computers scaling a drawing was more likely to be needed, for example to show details of a small object. However if your drawing will be read by others on a computer display they may use Zoom to view the details as close as desired. In this case it doesn't matter that the whole drawing spans 2 cm, just zoom in, all the detail is there.

Page Layout defines the size of the drawing. This provides the "room to work" by defining how many pages of paper make up the drawing. The size of a page of paper is defined by the Page Setup parameters. These parameters interact with your choice of scale to determine the size of the drawing on paper. This additional flexibility may allow a scale of 1:1 to be used in a wider range of circumstances. For example a drawing of a bread box could still be done at a scale of 1:1. Computer screen users of the drawing would zoom out to view the whole bread box. In Page Layout this drawing could be printed with a scale of 50% in Landscape mode and the bread box would fit on an 8" x 11" page of paper.

With these warnings in mind it is often very useful to use a scale for a drawing. For example when preparing a drawing for a BBC landscaping TV production, units of Yards and a scale of 1:120 will likely be useful.