Mac's built-in Preview app can visually crop a PDF but the crop is not always permanent — it stores a hidden border that other apps can reveal. Here is how to properly crop a PDF on Mac using a free browser tool that makes the crop stick.
Preview uses the PDF MediaBox to simulate a crop, but the data outside the boundary is still in the file. Apps like Adobe Reader, Chrome, and some printers can expose those hidden areas. For a reliable crop, you need a tool that rewrites the page boundaries.
On your Mac, open Safari, Chrome, or Firefox and go to pdfeditor.onl/crop-pdf. No download or installation is needed.
Drag your PDF from Finder into the upload area, or click to browse for the file. All pages render as previews.
Tip: You can also right-click a PDF in Finder, select Open With, and choose the browser to open it — then copy the path if needed.
Enter percentages for Top, Bottom, Left, and Right margins to remove. Use Uniform mode to crop all pages identically. The live preview lets you confirm the result.
Click Download. The cropped PDF saves directly to your Mac's Downloads folder via the browser. Open it in Preview or any app — the crop is now consistent everywhere.
Preview crops by setting a CropBox in the PDF, but some apps ignore the CropBox and display the full MediaBox instead. A proper crop tool rewrites the MediaBox itself, so there is nothing hidden to reveal.
Yes. The tool runs in any browser and is not dependent on the macOS version.
Once downloaded, the crop is applied. Always keep a copy of the original PDF before cropping if you might need to revert.