To change pixels to cm in Illustrator, open Edit > Preferences > Units (or Illustrator > Preferences > Units on macOS), switch the General dropdown from Pixels to Centimeters, and click OK — Illustrator will now display every width, height, position, and stroke size in centimeters instead of pixels. That change fixes the labels inside the panels, but it does not retroactively convert any pixel value you already have. If you are staring at a 1920-pixel-wide artboard, a 413-pixel ID photo, or a logo export tagged at 72 DPI and need to know what those numbers actually mean in centimeters, you still need a real conversion. The Pixels to CM Converter handles that second half: type a pixel value, pick a DPI, and read the equivalent in centimeters, millimeters, and inches side by side. Together, Illustrator's unit preference and the converter solve the full problem — telling Illustrator to think in centimeters, and turning pixel values into the physical size those numbers will actually print or render at.
Why Pixels and Centimeters Behave Differently in Illustrator
Pixels and centimeters describe completely different things. A pixel is a single colored point in a digital image and, on its own, has no physical size at all. A centimeter, by contrast, is a fixed physical length defined by the international system of units — one inch equals exactly 2.54 cm, which means 1 cm equals exactly 25.4 mm. The bridge between those two worlds is resolution, measured in DPI (dots per inch) or the closely related PPI (pixels per inch).
That is why Illustrator defaults to pixels for new documents aimed at screens, and to points, picas, or millimeters for print. When you design a poster that will be printed at A2 size, thinking in pixels is almost useless — the printer does not care about your pixel count, it cares about the physical dimensions of the paper and how many ink dots per inch it needs to lay down to hit those dimensions cleanly. When you design a UI mockup that will only ever be viewed on a screen, thinking in centimeters is overkill because screen sizes are already given to you in pixels by the operating system.
Most Illustrator users end up needing both views at different times. A freelance illustrator might receive a brief that says "make the cover 17 cm wide" while the source photographs they have been given are tagged in pixels. A UI designer might mock up a button at 96 px wide for a web preview and then need to tell a print vendor the same button in millimeters for a brochure. The unit change in Preferences handles the labels; a converter handles the numbers.
Switching Illustrator's Measurement Units to Centimeters
Illustrator lets you choose three independent measurement units: one for general geometry (the General setting), one for strokes, and one for type. For most design work, only the General setting matters, and that is the one you change first.
- Open Illustrator and choose Edit > Preferences > Units. On macOS, the menu path is Illustrator > Preferences > Units.
- In the Preferences window, find the Units section near the top of the dialog.
- Click the General dropdown — it usually shows Pixels, Points, Millimeters, Centimeters, Inches, or Picas depending on your locale.
- Select Centimeters. Optionally, change the Stroke dropdown to Centimeters as well if you want stroke widths to read in cm rather than points.
- Click OK to apply. Every numeric field in the Transform panel, Control panel, and Properties panel now reads in centimeters by default.
If you only need to override units for one specific value rather than the whole document, type the number with its unit suffix directly into any input box. Illustrator accepts mm, cm, in (inches), px (pixels), and pt (points). Typing "5cm" into the width field of a selected rectangle sets its width to 5 cm regardless of the General preference, and typing "1920px" sets it to 1920 pixels even when General is set to Centimeters. This on-the-fly override is the fastest way to mix units in one document without flipping preferences back and forth for every change.
Converting Pixel Values to Centimeters with the Pixels to CM Converter
Once Illustrator is showing centimeters, the next question is usually "okay, but my source image is 1920 pixels wide — how big is that in cm?" That is a math question, not a settings question, and the Pixels to CM Converter is built for exactly this step.
- Type a number into the converter and pick its starting unit — pixels, centimeters, inches, or millimeters — from the dropdown next to the field.
- Set the DPI. Click 96 for screen work, 300 for high-quality print, or type a custom value if your project uses something else (the tool accepts any number).
- Read the converted values for the remaining three units in the results table below the input — pixels, centimeters, inches, and millimeters update together the moment you change either the number or the DPI.
For a quick sanity check, try the cleanest case first: type 96, choose Pixels as the starting unit, set DPI to 96, and read the table. You should see 96 px = 1 inch = 2.54 cm = 25.4 mm. That single result is the anchor the rest of the unit system is built on, since 1 inch is defined as exactly 2.54 cm (the international inch fixed in 1959) and 1 inch at 96 DPI is exactly 96 pixels. Flip the DPI preset to 300 and watch the same 96 px input shrink into a noticeably smaller centimeter value — that visible jump is the clearest way to see why the DPI choice changes everything.
DPI Presets and When to Use Each
Picking the wrong resolution is the single most common mistake in pixel-to-cm conversions. The number on screen will look correct in pixels, but the printed result will either be tiny, blurry, or both. The table below lists the four DPI presets built into the converter, what each one is conventionally used for, and the kind of Illustrator project it fits.
| DPI | Typical use | Best for in Illustrator |
|---|---|---|
| 72 | Legacy web graphics, early desktop publishing | Archiving old assets, exporting for legacy web workflows |
| 96 | Modern web and screen rendering (CSS reference pixel) | UI mockups, social media assets, web banners |
| 150 | Draft-quality print, in-house print runs | Internal presentations, proofing, low-cost flyers |
| 300 | High-quality print, photo printing, professional output | Posters, packaging, ID photos, magazine spreads |
Web browsers and most modern screens use 96 DPI because the CSS specification defines the reference pixel as exactly 1/96 of an inch — that is why 96 is the default in the converter and the default assumption in any screen-design tool. Print is a different world. A high-quality print job at 300 DPI places 300 ink dots in every linear inch, which is roughly the threshold below which the human eye starts to see individual dots on coated paper at normal reading distance. Some legacy files are still tagged at 72 DPI because that value was the standard in early desktop publishing software, even though it is too low for any printed output today.
If your project lives between these presets — say, a 200 DPI export for a specific printer, or a 144 DPI asset for a high-density mobile screen — type the custom number into the DPI field. The converter accepts any number and updates all four unit columns instantly, so you do not need to choose one of the four presets if none of them match your workflow.
Common Conversion Scenarios for Illustrator Users
Three scenarios come up over and over in Illustrator work. The same converter handles all of them — the only thing that changes between them is the DPI preset you click.
ID and passport photos. Passport offices typically require physical sizes — a common width is 3.5 cm. Set the converter to 300 DPI, ask what pixel width matches 3.5 cm, and size your Illustrator artboard to that pixel count before exporting. Skipping this step is the most common reason ID photos come back from the print shop either blurry (too few pixels for the size) or visibly pixelated (resolution dropped too low).
Print posters and packaging. Anything leaving the screen for paper should be sized at 300 DPI unless the printer has specified otherwise. The same pixel count represents a much smaller physical footprint at 300 DPI than at 96 DPI, which is why an image that looks fine on screen can come back from the print shop far too small if you forgot to plan for print resolution. The converter makes that size difference visible the moment you switch the preset, which is the easiest way to catch a sizing mistake before sending files off.
Web and UI elements. If a client sends a brief in centimeters for what will actually be a web deliverable, work in 96 DPI. A button described as 4 cm wide becomes a specific pixel value at that DPI; the converter returns it instantly without you having to do the arithmetic, and the same 96 DPI assumption lets you sanity-check any pixel dimensions the engineering team delivers back. This round-trip — cm brief to px mockup to px implementation — is one of the most common day-to-day uses of pixel-to-centimeter conversion in design studios.
The whole chain — Illustrator set to centimeters, the converter for any pixel-to-cm number, and a DPI chosen for the medium the artwork will actually live on — covers the two halves of "change pixels to cm in Illustrator." Once those two pieces are in place, every artwork dimension you produce has a clear physical meaning, and you stop having to guess whether a pixel value will fit the paper, the screen, or the brief.
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