How does PDF cropping work?

Cropping resizes each page to the rectangle you choose by setting both its MediaBox and CropBox. The underlying content streams stay in the file, which is why cropped PDFs can usually be uncropped by another tool.

Will cropping reduce the file size?

Usually not by much. Cropping resizes the page boxes but the content streams are still there. To also shrink the file, run the compress PDF tool afterwards.

Can I apply different crops per page?

This tool applies one rectangle to all pages or just the first. For varying crops, split the PDF first and run the tool on each part.

Is my PDF uploaded anywhere?

All cropping runs in your browser using pdfjs-dist for rendering and pdf-lib for writing. Our servers are not involved at any point.

Crop PDF

PDF crop is a PDF tool that resizes each page to a rectangle you choose. It renders the first page with pdfjs-dist, lets you drag a crop rectangle (with optional aspect ratio lock for A4, Letter, or square), and writes a new PDF whose pages are resized to the cropped region by setting both the MediaBox and CropBox via pdf-lib. The tool runs in your browser.

Drop a PDF here or click to browse

Dedicated pages

Direct links for common cropping tasks.

Crop PDF Online

Crop pages of a PDF directly in your browser. Drag a crop rectangle on the first page preview, then apply to all pages or just the first. All processing runs in your browser.

Trim PDF Margins

Trim the white margins from a scanned or generated PDF. Drag the crop rectangle to keep only the body content. Runs entirely in your browser.

Crop PDF to a Specific Size

Crop a PDF to a custom rectangle or a chosen aspect ratio. Live preview on the first page, applied to every page with pdf-lib. Runs in your browser.

How to crop a PDF

Drop your PDF onto the upload area; the first page renders as a preview with a draggable rectangle.
Choose an aspect ratio (Free, 1:1, A4, Letter) and drag the rectangle to mark what to keep.
Choose whether to apply the crop to all pages or just the first.
Click Crop and download; pdf-lib writes a new PDF with each page resized to the crop rectangle.

Common uses

Trimming the white margins from a scanned document so the body fills more of the page. Combine with compress PDF to shrink the file too.
Cutting a single content area out of a multi-column report for archiving or quoting.
Fitting an oddly-sized PDF to a standard paper size (A4 or Letter) before printing.
Preparing a tight extract before converting the page to an image for use on the web.

Technical specification

Algorithm or formula: The first page is rendered to a canvas via pdfjs-dist. The user-drawn rectangle (in canvas pixels) is converted to PDF user-space points (1/72 inch) and written as both the page MediaBox and CropBox (ISO 32000-1 §14.11.2) via pdf-lib's page.setMediaBox() and page.setCropBox().
Browser API or library: pdfjs-dist for first-page rendering, pdf-lib for writing the CropBox on the chosen pages.
Input limits: PDF up to 100 MB.
Output: A new PDF with the same page count and same content streams. Each affected page is resized to the chosen rectangle by setting both its MediaBox and CropBox, so every viewer and printer treats the cropped region as the page.
Known limitations: One crop rectangle is applied to all selected pages. Pages whose dimensions differ from the previewed first page are skipped to avoid out-of-bounds CropBoxes. Encrypted PDFs must be unlocked first.

Frequently asked questions

How does PDF cropping work?: Cropping resizes each page to the rectangle you choose by setting both its MediaBox and CropBox. The underlying content streams stay in the file, which is why cropped PDFs can usually be uncropped by another tool.
Will cropping reduce the file size?: Usually not by much. Cropping resizes the page boxes but the content streams are still there. To also shrink the file, run the compress PDF tool afterwards.
Can I apply different crops per page?: This tool applies one rectangle to all pages or just the first. For varying crops, split the PDF first and run the tool on each part.
Is my PDF uploaded anywhere?: All cropping runs in your browser using pdfjs-dist for rendering and pdf-lib for writing. Our servers are not involved at any point.

Reviewed and tested May 26, 2026.