Printed Scale Verification

Measure one known dimension on the physical output to identify its effective scale, deviation and possible correction factor.

Known real length (m)Choose a clearly dimensioned, long horizontal or vertical check span. Measured length on print (mm)Measure the physical print after output, not the on-screen PDF. Stated scale denominator (1:n)

Enter a known real dimension, physical measurement and stated scale.

What this calculator solves

This checker belongs after the first sheet leaves the plotter and before a production set is released. It detects automatic page fitting, incorrect custom percentages and uniform device scaling errors that are invisible in the file metadata.

Use the job's defined tolerance. The displayed ±0.5% label is a diagnostic reference, not a universal contractual acceptance limit.

How to choose the inputs

Use a known dimension stated on the approved drawing, preferably a long span with precise endpoints. Enter its real length in metres and measure the matching physical span in millimetres. The denominator is the intended issue ratio.

Avoid folds, damaged areas and graphics that may have been inserted independently from the CAD geometry.

How the calculation works

Expected print length in millimetres = known real metres × 1,000 ÷ stated denominator. Effective denominator = known real millimetres ÷ measured print millimetres. Size deviation compares measured and expected physical lengths.

The correction factor is expected length ÷ measured length × 100. Apply it only if the file, page boxes, driver, media and orientation remain unchanged, then print and measure a new check sheet.

Worked production example

A 10 m known dimension should measure 200 mm at 1:50. If the plot measures 199 mm, its effective ratio is approximately 1:50.25 and it is 0.5% undersize. A theoretical correction is about 100.50%.

For a critical issue set, measure one horizontal and one vertical span. Equal deviation suggests uniform scaling; different deviations point to scanner, feed or media distortion that one percentage cannot safely correct.

How to interpret the result

The effective denominator describes the physical sheet. The signed deviation says whether it is large or small relative to nominal. Compare absolute deviation with the job tolerance, and treat the correction percentage as diagnostic until a second proof passes.

Common production mistakes

Do not use a short 10 mm graphic bar when a longer known dimension is available: ruler resolution dominates the result. Do not round the measured value before calculation or repeatedly compound correction percentages without returning to the approved baseline.

Paper can change after printing. Let media acclimatise when dimensional accuracy matters, and distinguish a plotter error from later moisture, heat or mounting movement.

Related production workflow

Calculate the intended percentage and sheet first, then use this page as the release gate. If the measurement fails, return to file and driver settings rather than changing approved CAD geometry.

Production assumptions and limitations

The correction assumes uniform linear scale and an accurate known dimension. A skewed scan, non-square pixel transformation or two-axis driver error needs separate diagnosis. Never scale from a drawing marked “Do not scale.”

Record the file revision, sheet, orientation, driver preset, stated ratio, known length, measured length and disposition. See Printing Plans to Scale and Drawing Scale Converter. Last reviewed: 2026-08-24.