My print came out too small. What percentage fixes it?

Intended divided by measured, as a percentage. If a 100 mm line printed at 96.8 mm, reprint at 100 ÷ 96.8 = 103.3%.

Why not just add the difference back?

Because scaling is multiplicative. A print that came out 5% small needs about 105.26%, not 105% — and the gap grows as the error grows.

Should I measure one direction or two?

Two. If the horizontal and vertical errors differ, the problem is not uniform scaling — it is non-uniform distortion, and a single correction percentage cannot fix it.

What causes the error in the first place?

Usually fit-to-page or “shrink oversized pages” in the print dialog, printing a different paper size than the drawing was set up for, or photocopying. Printing at 100% / actual size avoids all three.

Print correction

Print scale correction calculator

Measure a known dimension on a print that came out wrong and get the exact reprint percentage. Measure both axes and the diagnostic tells you whether you have a uniform scaling error you can correct, or non-uniform distortion you cannot.

What it should be, what it is

Expected X measurement

From the drawing or model.

Measured X measurement

What a ruler says on the print.

Also check a second axis

Strongly recommended: it is the only way to detect non-uniform output.

Expected Y measurement

Measured Y measurement

I know the intended drawing scale

Adds the effective scale the print actually ended up at.

Re-print at

106.382978…%

The print came out at 94% of the intended size. Re-printing the same file at 106.382978…% should restore the intended scale.

Assumes the printer applies your percentage exactly and that your measurement is accurate. Verify the re-print before relying on it.

What happened, step by step

1. Expected100 mmFrom the drawing
2. Measured94 mmOn the sheet
3. Observed scale94%0.94× of intended
4. Required correction106.382978…%Re-print at this

X observed factor: 0.94×
X correction: 106.382978…%
Y observed factor: 0.94×
Y correction: 106.382978…%

How this was calculated

Inputs

Expected X: 100 mm
Measured X: 94 mm
Expected Y: 50 mm
Measured Y: 47 mm

Formula

observed k = measured ÷ expected; correction = 1 ÷ observed k

X: 94 mm ÷ 100 mm = 0.94× Y: 47 mm ÷ 50 mm = 0.94×

correction = 106.382978…%

Exact calculation state: 50/47 — displayed values are formatted from this fraction, never re-used after rounding.

Calculated by SnapScaleCalc from the values entered. Methodology

How this calculation works

The print applied some unknown factor. Measuring one known dimension recovers it:

k_applied = measured ÷ intended | correction = intended ÷ measured

The correction is the reciprocal of what happened, and it applies to the original file at 100%, not to the already-wrong print. Both figures are exact fractions of your two measurements.

Two axes, two answers

When you supply horizontal and vertical measurements, the calculator compares the two recovered factors. If they agree, the error is uniform and one reprint percentage fixes it. If they differ, the output is stretched — from non-square printer scaling, a skewed scan, or paper that moved — and no single percentage can restore it. The calculator says so instead of averaging the two into a plausible-looking wrong answer.

Choosing the reference dimension

Measure the longest dimension whose intended value you know for certain — a title-block scale bar, a sheet border, a stated dimension. Short references magnify measurement error into the correction percentage.

What this does not tell you

A corrected reprint restores dimensions, not fidelity. Detail lost to a raster copy or a coarse scan stays lost, and repeated copying softens lines regardless of scale. Wherever the source file exists, print it at 100% instead of correcting a copy.

Paper is also not stable: it expands and contracts with humidity, and large sheets can move enough to matter at fine tolerances. For anything dimensionally critical, verify against the written dimensions rather than the paper.

Questions people ask about this

My print came out too small. What percentage fixes it?: Intended divided by measured, as a percentage. If a 100 mm line printed at 96.8 mm, reprint at 100 ÷ 96.8 = 103.3%.
Why not just add the difference back?: Because scaling is multiplicative. A print that came out 5% small needs about 105.26%, not 105% — and the gap grows as the error grows.
Should I measure one direction or two?: Two. If the horizontal and vertical errors differ, the problem is not uniform scaling — it is non-uniform distortion, and a single correction percentage cannot fix it.
What causes the error in the first place?: Usually fit-to-page or “shrink oversized pages” in the print dialog, printing a different paper size than the drawing was set up for, or photocopying. Printing at 100% / actual size avoids all three.