SynthPDF

Crop PDF

Trim margins from all pages of your PDF.

Set how many points (1 pt ≈ 0.35 mm) to crop from each edge.

Crop PDF

Upload a PDF to preview pages

How It Works

1

Upload your PDF

Drop in any PDF. A visual preview of the first page appears for crop area selection.

2

Set the crop area

Drag the crop handles to define the area to keep. Apply to all pages or individual pages.

3

Download cropped PDF

The selected content area is kept; everything outside is trimmed. Download instantly.

When to Crop a PDF

Cropping is useful whenever you need to change the visible area of a PDF page without changing the underlying content. Common scenarios:

  • Remove excessive white margins — academic papers and scanned books often have large margins that waste screen space on tablets and e-readers
  • Remove headers and footers — strip repeating page headers, footers, and page numbers before repurposing content
  • Crop to content — trim a PDF down to just the relevant chart or figure for use in a presentation
  • Standardise page size — some PDFs have inconsistent margins; crop to a uniform content area
  • Remove watermarks in margins — if watermarks are in the page margin area, cropping removes them (note: watermarks in the main content area are not removed by cropping)

Understanding the PDF Crop Box

PDFs have several "box" definitions that control how the page is displayed and printed:

  • MediaBox — the full page dimensions, including bleed area
  • CropBox — the visible area displayed in PDF viewers (what cropping changes)
  • BleedBox, TrimBox, ArtBox — print production boxes, less commonly used in everyday documents

When you crop a PDF, we update the CropBox. The underlying content outside the crop area remains in the file — it's just hidden. This is why cropping doesn't significantly reduce file size.

Crop vs Other Editing Tools

  • Crop — changes the visible area; underlying content outside the crop is preserved
  • Redact — permanently removes content; use when sensitive information needs to be gone, not just hidden
  • Remove Pages — deletes entire pages; use when you want to remove whole pages rather than trim the edges of pages

Frequently Asked Questions

Not significantly — PDF cropping changes the visible area (the crop box) but the full page content remains in the file. For true size reduction, use Compress PDF after cropping.

Yes — apply different crop areas to different pages, or apply one crop to all pages at once.

Yes — set the crop area to exclude the header and footer regions. This is a common use case for academic papers and scanned books.

Yes — cropping adjusts the visible area, it doesn't rasterise the content. Text, links, and all PDF features remain intact.

Yes — scanned PDFs are images embedded in PDF pages. Cropping works the same way and removes the unwanted image area from view.

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