How to Merge, Split, and Compress PDF Files on Windows

Choose the Right PDF Task

You do not need to run all three operations. A report packet may need merging and compression; a document sent to different reviewers may need splitting only.

Before you start

• Keep the original PDFs and save results to a separate folder.
• Open each source once to check that it is readable and complete.
• For a merged packet, make a short list of the intended document order.
• Check the recipient's actual attachment or upload limit before choosing compression settings.

How to Merge PDF Files into One Document

Use this for a cover sheet, report, and supporting documents that should arrive as one packet. The Formathor merge workspace provides an output folder, an output file name, and an optional Unify page width setting.

1. Open the Merge PDF workspace.

   Launch GiliSoft Formathor, select PDF Tools at the top, then choose Merge PDF on the left.

2. Add the source PDFs and check their sequence.

   Click Add Files or use the drop area. Check the displayed file order before continuing; do not assume that selecting files in Explorer guarantees the intended reading order.

3. Set the output folder and file name.

   Under Merge Presets, choose Output and enter an Output file name. Leave Unify page width unchecked when original page dimensions matter; test a copy with it enabled if consistent page width is required.

4. Merge and inspect the new document.

   Click Merge. Open the saved PDF, check where each source begins and ends, and compare its page count with the source documents.

Example: a 2-page cover letter, a 10-page report, and a 3-page appendix should produce a 15-page packet when all source pages are included. Check the transitions between those documents, not just the first page.

How to Split a PDF into Separate Files

Splitting changes how the content is packaged. It does not automatically remove sensitive information or reduce the quality of scanned pages.

1. Select Split PDF.

   In GiliSoft Formathor, open PDF Tools > Split PDF.

2. Add one PDF for a test.

   Click Add Files and select the source. Check any settings available after import against the output you need.

3. Choose a separate output folder.

   Set Output under Split Presets. An empty destination folder makes it easier to identify and inspect the generated files.

4. Run the split and review every output.

   Click Split. Check the resulting file names, page counts, and first and last pages before distributing the files.

How to Compress a PDF for Email or Upload

Compression is the right task when all pages must stay together but the file exceeds the delivery limit. Image resolution and other embedded content can contribute to a large PDF; the achievable reduction varies by file.

1. Open Compress PDF and add your file.

   Choose PDF Tools > Compress PDF in GiliSoft Formathor, then click Add Files.

2. Start with the Medium compression preset.

   The screenshot shows Medium in the Compression list. Use it as a first test, then compare the result with the original before trying another available setting.

3. Choose where to save the compressed copy.

   Set Output to a separate folder under Compression Presets, then click Compress.

4. Compare size and readability.

   Check the saved file's size in Windows File Explorer. Open the PDF and inspect small text, scanned stamps, diagrams, and photographs at normal reading size and when zoomed in.

Do not repeatedly compress the same output to chase a smaller number. Return to the original for another test. If the PDF still exceeds the limit, consider splitting it when permitted or using an approved file-sharing method.

Compression can involve quality trade-offs. Compare small text, images, and diagrams in the saved PDF with the original, and choose the setting that meets your delivery limit without sacrificing necessary detail.

Check the Final PDF Before Sharing

For one combined packet, a practical order is merge → verify → compress if needed → verify again. For separate recipients, split first and check each output individually. Apply any required protection only after document preparation, then test access to the final copy.

• Content: expected pages are present, in order, with no accidental duplicates.
• Readability: small text, charts, scans, and photographs remain usable.
• Function: test important links, bookmarks, searchable text, or form fields rather than assuming they were preserved.
• Delivery: confirm the actual output size, file name, destination, and recipient permissions.

Common PDF Processing Problems

The merged pages are in the wrong order

Check the source file sequence and confirm each source's internal page order. Rebuild the packet from the originals. When documents have mixed dimensions, inspect the effect of the page-width option separately.

The compressed PDF is still too large

The source may already be optimized or contain content that is difficult to reduce further. Check whether a smaller output is worth the loss of detail; a lower file size is not useful if the document becomes unreadable. See why a PDF can be too large to email.

The file will not open or process

Open the source in a PDF viewer first. Check whether a password is required, the download is incomplete, or the destination folder is writable. Try one ordinary, unprotected PDF to separate a source-file problem from a setup problem.

The split output is not the section I expected

Inspect the available split settings after import and check the generated files before sending them. If your required range or chapter mode is unavailable, use a tool with that specific page-selection feature.

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