A drawing doesn't know its real size until you tell it. Every part on a page is measured from that page's scale, so set it before you trust any area or price. Until a page has a scale, the Takeoff shows a short guide at the bottom of the canvas, and parts on that page aren't measured.
Draw along a known length#
This works on every file, PDF or image.
- Press Scale in the tool palette, or S.
- Zoom in on something whose real size you know: a printed dimension, or a feature such as a door you've measured.
- Drag from one end to the other. The line snaps to corners of the artwork; hold Alt to place it freely.
- Type the real length and pick the unit: in, ft, mm, cm or m. For example, draw along a callout that reads 48 in
and enter
48in. - Press Save scale.
When there is a dimension printed near your line, such as "48 in" or "1200 mm" (including measurement notes made in PDF software), the dialog offers it as Detected. Check that it belongs to the line you drew before you save.
The preview in the dialog shows what the scale works out to, and how many unmeasured parts on the page will adopt it.
Use the drawing ratio#
PDFs drawn to a stated scale can use it directly. Open the scale dialog, choose Drawing ratio and enter the second
number: 1 : 20 means 1 inch on the page is 20 inches in real life. Actual size (1:1) is for print-ready files
drawn at full size. The ratio isn't offered for images, because an image's pixels have no physical size.
Several views on one page#
A page often shows several views at different scales, such as a vehicle's side and its back. Add a scale for each view and name it after the view. Each scale gets its own colour, and each part uses one scale: pick it in the part's Scale field, or select several parts and use Set scale for all….
Check the scale#
A scale line a few pixels off is a percentage off on every part. Always check against a second dimension you know:
- Press Dimension line (M) and draw it along another known length, far from the first.
- Compare the reading with the real value.
If the two agree to within your drawing accuracy, the scale is good. If the reading is off by a steady percentage, the scale is wrong: redraw the scale line. Draw along the longest dimension you know, zoomed in, so a small slip at the ends matters less. If one reading is off and others agree, the drawing itself may not be to scale at that spot (a proof that was stretched, or a callout that rounds).
Limits#
A known length can be at most 100,000 in (2,540 m), and a ratio at most 1:10,000. A scale line so short that one page unit would be more than 1,000 in is refused as too coarse: draw a longer reference line.