: How many InDesign points to a milimeter? (and mm to pt) What's the conversion between InDesign's point measurement (as used in leading and text size etc) and millimetres? What's the pt : mm

@Si6392903

In Adobe InDesign (don't know how it is in other adobe softwares) it's a bit more complicated actually BECAUSE OF the accuracy of InDesign's interpretation of decimals.

To test Evan's values I made a simple experiment:

When you set the baseline grid increment (edit > preferences > grids > baseline grid) to the value of 1 pt and then on the page you will create a rectangle snapped to the two nearest baseline grid lines... you will end up with a rectangle of a height of exactly 0.353 mm.

Why?

Because InDesign apparently rounds the values of 1 point (0.352777778 mm) to the three decimal places (therefore 0.353 mm).

So:


IN THEORY: 1 PostScript point = 0.352777778 mm
IN INDESIGN: 1 PostScript point = 0.353 mm
DIFFERENCE: 0.353 mm - 0.352777778 mm = 0.000222222 mm


It seems not important, but becomes a problem, when you will need to multiply the values for some reasons. Let's say you have 250 baseline grid lines incrementing by 1 pt, and you need to create a rectangle of exactly the height of those 250 lines.


IN THEORY: 250 * 0.352777778 mm = 88.1944445 mm
IN INDESIGN: 250 * 0.353 mm = 88.25 mm
DIFFERENCE: 88.25 mm - 88.1944445 mm = 0.0555555 mm


So the seemingly negligible INDESIGN/THEORY difference on the level of 1 point unit interpretation (0.353 mm - 0.352777778 mm = 0.000222222 mm) becomes "magically" more important after multiplication (88.25 mm - 88.1944445 mm = 0.0555555 mm)

Hope it helps! :)

PS: Or maybe We can just set the InDesign's default accuracy to higher values then three decimal places? If so all that I have written above is bullshit. But I don't know if such accuracy setting is somewhere available in InDesign. Maybe someone know?

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@Odierno310

1 pt is equal to

0.08333 picas

0.01389 inches

0.3528 mm (millimeters)

one nice feature in basically all of adobe's software is that it can do those conversions for you. You can simply type in any of the unit of measure and it will even do basic math for you too like +2mm

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@Kaufman565

"Points" in typography e.g. in Indesign, Illustrator, Photoshop etc are "PostScript points" and, helpfully, they're a unit Google converts on searches like points to mm or mm to points.

Has to be points or postscript points, not pts or anything involving software names.



One point is 0.352777778 millimetres.



One millimetre is 2.83464567 PostScript points.

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