Cropping a PDF means changing the visible frame of each page — the rectangle a PDF reader uses to decide what to show — so the white borders, scanner edges, or extra header space around your content are hidden from view. PDF-XChange Editor handles this through its Crop Pages tool, which lets you select margins in inches or millimeters and applies the same trim to the pages you pick. The same result is possible without installing anything: Crop PDF runs entirely in your browser, takes margins in points (72 pt = 1 inch), millimeters, or as a percentage of the page size, and applies them to every page in one click. Both methods work by adjusting each page's CropBox rather than deleting content, so text and images outside the new frame stay inside the file — just hidden. That non-destructive design is why cropping is fast, reversible, and safe to experiment with, but it is also why cropping is not a substitute for redaction when you need to permanently remove sensitive information from a document.
What Cropping a PDF Actually Changes
Every page in a PDF is described by a small set of rectangles that control how it is displayed and printed. The MediaBox defines the original full page — essentially the sheet of paper that was scanned, printed, or exported. The CropBox is an additional frame nested inside the MediaBox that tells viewers "show only this region of the page." When you crop, you shrink or shift the CropBox; the MediaBox itself is left alone.
The practical consequence is that any text, image, or vector artwork that falls outside the new CropBox still exists in the file. A PDF reader following the PDF specification will simply not draw that content because it lies outside the visible rectangle. That is why professional editors — and tools that mimic them — treat cropping as a viewing operation rather than an editing one.
Because the original content is preserved, cropping is fully reversible: opening the same PDF in another tool, or returning to this one with zero margins on every side, restores the original view. The trade-off is that cropping is not a security tool. If you need to permanently remove a Social Security number, a bank balance, or any other sensitive value from a document before sharing it, use a dedicated redaction workflow that overwrites or flattens the underlying content stream.
Cropping a PDF in PDF-XChange Editor
PDF-XChange Editor is a Windows desktop application that bundles viewing, OCR, and page editing in a single installer. Cropping is built into its page-editing toolkit, and it follows the same general pattern as other professional PDF editors. If you already have it installed, the typical workflow for trimming margins looks like this:
- Open your PDF in PDF-XChange Editor using File → Open, or drag the file onto the application window.
- Switch to the page thumbnails panel and select which pages should receive the crop. To crop the whole document, select all pages; for a single page, leave the selection on the current page.
- Open the Crop Pages dialog. In PDF-XChange Editor this is found under the page-editing menu and is also reachable by right-clicking a thumbnail.
- Enter values for the Top, Bottom, Left, and Right margins. PDF-XChange Editor accepts inches or millimeters in this dialog.
- Choose which pages the crop applies to — current page, selected pages, odd pages, even pages, or all pages in the document — and confirm.
- Save the result with Ctrl+S, or use File → Save As to keep a separate cropped copy alongside the original.
The desktop workflow is genuinely powerful: it supports per-page margins, odd/even page targeting, and re-saving with or without re-encoding. The cost is the installer itself — roughly 200 MB on disk, plus the time and admin rights to set it up. For one-off jobs, or for users who do not have a Windows machine to hand, the same effect is reachable through a browser tool. A side-by-side look at desktop versus browser cropping is collected in How to Crop a PDF Using Foxit and Browser Alternatives.
A No-Install Alternative: Cropping in Your Browser
When installing software is not an option — a locked-down work laptop, a shared computer, a Chromebook — the Crop PDF tool produces the same kind of cropped output without leaving the browser. Everything happens locally in JavaScript; the file is read into memory on your device and processed there. No copy is sent to a server, which makes the tool safe for contracts, medical records, and financial statements. Here is the full procedure:
- Open Crop PDF in your browser and click Browse PDF to pick the file you want to crop, or drag the file onto the page. The tool reads the file locally.
- Choose a margin unit from the dropdown: points, millimeters, or percent. The page-size hint updates immediately so you can see the current dimensions in your chosen unit.
- Enter how much to trim from the Top, Right, Bottom, and Left of every page. You can switch units at any time without re-uploading.
- Click Crop PDF. The tool computes a new CropBox for each page (with the origin at the bottom-left of the page, so x = left, y = bottom, width = MediaBox width − left − right, height = MediaBox height − top − bottom) and builds a fresh PDF.
- Download the cropped copy from the result link that appears. Your original file is untouched; you keep a new, trimmed version alongside it.
Built-in validation stops you before you accidentally crop the entire page or enter a negative number, and the same trim is applied to every page in the document — which is exactly what you want for slide decks, scanned book chapters, and uniform reports.
Picking Margin Values and Units
Three units are available because three audiences tend to think in three different languages. Printers and PDF professionals measure in points, where 72 points equal one inch — the PDF specification uses points as its native user-space unit. Office workers tend to think in millimeters. Designers who are used to responsive layouts often prefer percent, because a 5 percent trim scales sensibly across pages of different sizes. The table below lists the official relationships between these units.
| Unit | Symbol | Equivalent |
|---|---|---|
| 1 point | pt | 1/72 inch (defined by the PDF specification) |
| 1 inch | in | 72 points = 25.4 millimeters (exact) |
| 1 millimeter | mm | 2.83464567 points |
| 1 percent | % | 1% of the page size |
To convert a margin manually, multiply millimeters by 72 and divide by 25.4. For example, a 15 mm trim becomes 15 × 72 / 25.4 = 42.520 points, which rounds to roughly 42.5 pt. The conversion is exact and works in either direction.
A practical starting point for typical scans is 20 to 30 points (about 7 to 10 mm) on the side that carries the worst scanner border. Slide decks usually need 30 to 50 points trimmed from the top to remove the application chrome. Books exported to PDF often look balanced after removing 5 percent from every edge.
Edge Cases — Rotated Pages, Passwords, and Reversing a Crop
Three situations deserve a moment of attention before you press the button. The first is already-cropped PDFs. Crop margins are always measured from the original full page (the MediaBox), so cropping a file that was previously cropped resets the previous crop rather than trimming further from the visible frame. If your goal is to add to an existing crop, undo the previous one first.
The second is rotated pages. Many phone scans carry a rotation flag that re-orients the page at view time without rotating the underlying content. Margins are applied to the unrotated orientation, so the label "Top" may not match the edge you see on screen. The browser tool surfaces a note when it detects this, so pay attention to the page-size hint and the rotation indicator before entering values.
The third is password-protected or corrupted PDFs. Files that require an open password cannot be read without it, and the tool will surface that fact rather than silently producing a broken output. Unlock the PDF first — PDF-XChange Editor can do this from the File menu — then come back to crop. None of this changes the original; the only file that is altered is the new download the tool gives you. Because cropping only changes the CropBox, you can always re-open the cropped PDF in the same tool with zero margins to restore the original view.
Combining Cropping With Other Browser-Based PDF Tools
Cropping is rarely the only fix a PDF needs. Scanned chapters usually need page numbers added, contracts often need a signature, and reports frequently need to be split or merged before they reach a reader. Because Crop PDF runs entirely in the browser and leaves your original untouched, you can chain it with the rest of the no-upload PDF toolkit to build a full cleanup routine: Rotate PDF for sideways phone scans, Merge PDF to combine chapters after trimming, Split PDF to break a cropped document into separate sections, and Extract PDF Pages to pull out the pages that matter. The same privacy guarantees apply across the board: every byte stays on your device from the moment you pick the file to the moment you download the result.