Why does a PDF takeoff need calibration?
Screen pixels have no physical meaning on their own. Calibration links a known page-coordinate distance to a real unit, after which lengths and polygon areas can be recalculated independently of display zoom.
How to use the PDF Measurement Tool
- Step 1Open a drawing, choose Calibrate and click two known points.
- Step 2Enter the real distance and create length, polyline, area or count measurements.
- Step 3Manage the takeoff list and export CSV or a printable summary.
Formula / How it works
Physical length = page-coordinate length × calibrated real distance ÷ calibration page distance.
Example
Calibrate a known 5 m dimension, then measure lengths and polygon areas without zoom changing the result.
PDF Measurement Tool FAQ
Does zoom change a measurement?
No. Geometry is stored in PDF page coordinates and zoom only changes rendering.
Can every page use a different scale?
Yes. Calibration is stored per page because multi-page drawing sets can contain different scales.
Is this survey-grade?
No. Accuracy depends on the source drawing, correct calibration and careful point placement.
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