Scale

How a sheet is told what it measures, and which scale wins when more than one applies.

Every measurement on a page comes from that page's scale. Nothing measures correctly until the scale is right, and nothing warns you that it is wrong, because a wrong scale produces perfectly plausible numbers.

Scale can be set three ways, all the same editor reached from different places:

• Typed, by picking a preset or entering the equation. See Setting a scale.
• Measured, by calibrating against a distance you know. See Calibrating.
• Per layer, where one layer is drawn at a different scale from the rest of the sheet. See Layer scales.

Which scale applies

When something is measured, the first of these that is set wins:

1. The layer's own scale, if the layer being measured on has one.
2. The page's scale. This is the normal case.
3. A default, whose numbers mean nothing in particular.

A layer scale is therefore an override, not an addition. It does not combine with the page's scale; it replaces it for everything measured on that layer.