# Crop PDF — Technical Tool Documentation > **Summary:** Change the visible crop box using page margins. > **Tool Route:** `/tools/crop.html` > **Visual Guide Route:** `/guides/crop-pdf/` > **Category:** Edit PDF > **Processing Architecture:** 100% Client-Side. Zero server uploads. --- ## 1. What the Tool Does Crop PDF adjusts the visible page bounds with top, bottom, left, and right margins. It can apply the change to all, odd, or even pages. **Requirements & Constraints:** One readable PDF is required. Margin values are points and should leave a positive page area. --- ## 2. When to Use It Use **Crop PDF** whenever you need to perform client-side edit pdf operations without uploading confidential records to third-party cloud servers. **Ideal Scenarios:** - Working on personal identity records, banking statements, medical filings, or NDAs requiring 100% local confidentiality. - Fast offline or low-bandwidth processing directly in your web browser. - Universal cross-platform document operations on Windows, macOS, Linux, Android, or iOS. --- ## 3. Key Implemented Features - **Engine Architecture:** `pdf-lib (page.setCropBox, page.setMediaBox)` - **Zero Server Uploads:** Processing executes directly within client browser memory. - **Instant Processing:** Fast execution powered by WebAssembly and native HTML5 APIs. - **Review Previews:** Visual feedback and progress indicators confirm results prior to saving. - **No Sign-up / No Watermarks:** Full functionality with zero paywalls or forced branding. --- ## 4. Supported Input Files - **Primary Input:** Single PDF document (.pdf) - **Validation:** Files are validated in the browser prior to parsing. --- ## 5. Supported Output Files - **Output Format:** Cropped PDF document (cropped.pdf) - **MIME Types:** `application/pdf` (or appropriate image/text/zip formats). --- ## 6. File Size & Memory Limits - **Recommended Bounds:** Client RAM bound - **Technical Context:** Modern browser tabs enforce memory quotas (typically 1.5 GB to 2 GB per tab). PDFHub handles documents comfortably within standard browser memory limits. For files exceeding 150 MB or 1,000 pages, splitting into smaller sections is recommended. --- ## 7. Step-by-Step Instructions 1. **Upload a PDF to Crop PDF.** 2. **Enter top, bottom, left, and right margins in points.** 3. **Choose whether to apply the margins to all, odd, or even pages.** 4. **Select Crop PDF and inspect the resulting page edges.** --- ## 8. Required User Inputs & Controls - **File Upload Area (`#drop` / `#fin`):** Click to open native file browser or drag and drop supported files. - **Tool Options (`#opts`):** Dynamic settings panel configuring parameters, page ranges, or compression levels. - **Execution Button (`Crop PDF (#goBtn)`):** Triggers client-side processing pipeline. - **Reset Button:** Clears loaded files and resets workspace to pristine state. --- ## 9. Processing Behavior & Execution Pipeline Reads MediaBox dimensions, subtracts user-specified margin offsets (top, bottom, left, right in points), sets new CropBox rectangle boundaries on selected pages, and outputs trimmed PDF. --- ## 10. Expected Output & Download Verification - Upon successful execution, the interface triggers an automated browser download via `downloadBlob()` or opens a result review modal. - Users can verify file size, page count, and visual rendering before finalizing the download. --- ## 11. Practical Example Use Case Trimming printer bleed marks, header stamps, or excessive white margins from eBooks or academic articles. --- ## 12. Common Errors & Troubleshooting - **Issue:** If the output is blank or clipped, retry with smaller margins. - **Issue:** If the file cannot be read, use a valid, unencrypted PDF. - **Avoid:** Entering margins larger than the page dimensions. - **Avoid:** Confusing cropping with deleting content; the original content may still exist outside the crop box. - **Tip:** Entering margin offsets larger than page dimensions causing inverted crop boxes. Solution: Use modest values (20–50 pt). --- ## 13. Privacy & Data Handling Architecture - **Local Processing:** 100% Client-Side. Zero server uploads. - **Browser Memory:** Document bytes reside temporarily in `ArrayBuffer` memory and are garbage collected when the browser tab is refreshed or closed. - **Cookies & Telemetry:** PDFHub sets zero tracking cookies, zero analytics beacons, and stores zero personal document data. --- ## 14. Frequently Asked Questions (FAQ) #### Q: Can I crop individual pages? **A:** This page applies the setting by page parity, not individually. #### Q: Does cropping remove content permanently? **A:** It changes visible bounds rather than redrawing content. --- ## 15. Related PDFHub Tools - [Rotate PDF Documentation](rotate-pdf.md) - [Edit PDF Documentation](edit-pdf.md) - [Organize PDF Documentation](organize-pdf.md) --- ## 16. Links & Resources - **Launch Live Tool:** [Open Crop PDF in PDFHub](../../tools/crop.html) - **Visual Tutorial:** [View Crop PDF Visual Guide](../../guides/crop-pdf/) - **All Tools Master Reference:** [All Tools Reference](../all-tools-reference.md) - **Master Documentation Index:** [Documentation Index](../documentation-index.md) --- ## 17. Visual Walkthrough & Interface Screenshots ### Step 1: Open Crop PDF - **Interface Control:** `Upload Drop Zone (#drop)` - **What You See:** The upload drop area accepts any PDF document. - **What to Do:** Open Crop PDF to trim excess margins, printer marks, or unwanted borders. - **Practical Pro-Tip:** Cropping adjusts the visible page boundary (CropBox) without deleting underlying content. ![Crop PDF Step 1 - Open Crop PDF](../images/crop-pdf-step-1.png) ### Step 2: Upload PDF Document - **Interface Control:** `File Browser (#fin)` - **What You See:** The document loads and renders a visual preview canvas with boundary boxes. - **What to Do:** Select your PDF document with margins you want to trim. - **Practical Pro-Tip:** You can crop all pages uniformly or target individual sheets. ![Crop PDF Step 2 - Upload PDF Document](../images/crop-pdf-step-2.png) ### Step 3: Choose Target Pages - **Interface Control:** `Target Dropdown (#applyTo)` - **What You See:** The selector ensures crop margins apply consistently across your target range. - **What to Do:** Select whether to crop "All pages", "First page only", or "Current page". - **Practical Pro-Tip:** Standard books and scan batches usually require uniform margin cropping. ![Crop PDF Step 3 - Choose Target Pages](../images/crop-pdf-step-3.png) ### Step 4: Enter Margin Trim Values - **Interface Control:** `Margin Inputs (#top, #bottom, #left, #right)` - **What You See:** The input fields register trim depths for each border. - **What to Do:** Enter the points to trim from the Top, Bottom, Left, and Right edges (e.g. 36pt = 0.5 inch). - **Practical Pro-Tip:** 72 points equals 1 inch (25.4mm). A 36pt trim removes exactly half an inch. ![Crop PDF Step 4 - Enter Margin Trim Values](../images/crop-pdf-step-4.png) ### Step 5: Inspect Crop Box on Canvas - **Interface Control:** `Canvas Bounding Box (#cropCanvas)` - **What You See:** The overlay rectangle shows the exact area that will be retained. - **What to Do:** Observe the highlighted crop boundary rectangle on the visual preview canvas. - **Practical Pro-Tip:** Make sure headings, page numbers, and footnotes remain comfortably inside the box. ![Crop PDF Step 5 - Inspect Crop Box on Canvas](../images/crop-pdf-step-4.png) ### Step 6: Click Crop PDF - **Interface Control:** `Crop Action Button (#goBtn)` - **What You See:** The client-side engine recalculates the page MediaBox and CropBox geometry. - **What to Do:** Click the primary "Crop PDF" button. - **Practical Pro-Tip:** The cropped file opens cleanly in all standard PDF viewers with trimmed margins. ![Crop PDF Step 6 - Click Crop PDF](../images/crop-pdf-step-4.png) ### Step 7: Review Cropped Document & Download - **Interface Control:** `Preview Section & Download (#generatedPreview, #dlModal)` - **What You See:** The preview displays the clean, trimmed document without excess borders. - **What to Do:** Inspect the trimmed pages in the preview viewer, then click "Download". - **Practical Pro-Tip:** Your trimmed document is now ready for e-readers, tablets, or compact printing. ![Crop PDF Step 7 - Review Cropped Document & Download](../images/crop-pdf-step-4.png)