Scale calibration

Every measurement in Plan Markup depends on the sheet’s scale. Calibrate before you measure, and re-check it on every sheet you take quantities from. A wrong scale does not look wrong on screen. It looks wrong in your bid.

There are two ways to set a scale.

Trace a known dimension

The most reliable method, and the one to use when you do not trust the title block:

1. Open the scale dialog and choose to calibrate.
2. Click one end of a dimension you know, then click the other end. A dimension string on the drawing is the usual pick.
3. Type what that distance really is.

Two clicks and a number, and the sheet is calibrated. This works even on sheets that were printed at an odd size or scanned slightly off, because you are measuring the sheet as it actually is, not as the title block claims it should be.

Tip

Trace the longest clearly dimensioned run you can find. A small error on a 4 foot dimension compounds a lot worse than the same error on a 100 foot one.

Pick a standard scale

If the sheet is true to its stated scale, pick it from the preset list instead. Plan Markup ships the common architectural and civil scales, from 1/16“ = 1’-0“ up through 1“ = 100’, including 1/8“ = 1’-0“, 1/4“ = 1’-0“, 1“ = 20’, 1“ = 30’, and the rest of the usual suspects.

Caution

Presets assume the PDF is at its printed size. Half-size prints and re-scaled scans will read wrong with a preset. When in doubt, trace a known dimension instead.

Per page, or all pages

Scale is stored per page, because real plan sets mix scales: the site plan at 1“ = 30’, details at 1/2“ = 1’-0“, an enlarged plan at something else again. When a whole set shares one scale, apply the scale to all pages in one step instead of walking every sheet.

The calibration lives in the sidecar file next to the PDF, alongside the markups. Calibrate a sheet once on your Mac and the browser app sees the same scale, and the other way around.

What happens without a scale

The drawing tools all work without calibration. You can cloud, note, and highlight a sheet you never measure. But length, area, and count measurements only mean something once the page has a scale, so make calibration the first move on any sheet feeding your takeoff.