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To keep text readable when compressing a PDF in SwifDoo, make a copy of the file, choose the quality-preserving option first, and inspect the compressed copy before sharing or replacing the original. If the file is still too large, try medium compression and compare the result page by page.

Choose a compression level that fits your PDF

Compression trades file size against image quality. SwifDoo’s mobile guides describe three choices: Less Quality, High Compression, Medium Quality, Good Compression, and High Quality, Less Compression. The wording makes the compromise clear: more compression can mean less visual detail. These are vendor-described levels, not a guarantee that one setting will preserve every document equally.

  • High Quality, Less Compression: Start here when clear text matters more than achieving the smallest file.
  • Medium Quality, Good Compression: Try this if you need a smaller file, especially for a PDF containing both text and images. SwifDoo recommends medium compression for mixed-content documents in its Windows compression guide.
  • Less Quality, High Compression: Use only if the larger reduction is worth the risk of softer or less distinct details. Check small text and image content carefully afterward.

The options and labels may differ between operating systems or app versions, so use the choices shown in your installed version.

Compress a PDF in SwifDoo on Windows

  1. Keep an untouched original. Make a duplicate of the PDF and open the duplicate in SwifDoo PDF.
  2. Go to Edit > Compress.
  3. Select a compression level. For text-first documents, begin with the least-compressive, quality-preserving option available. For mixed text and images, SwifDoo describes Medium Compression as a balance.
  4. Select Start, then save the optimized PDF as a separate file.
  5. Open the saved file and check the pages and details listed below before sending it. SwifDoo’s guide also describes a Custom option for controlling image DPI targets and JPEG quality; consider it only if those controls are present in your version and you know which tradeoffs you need. See the SwifDoo Windows compression instructions.

SwifDoo’s Windows interface and labels can change between versions. If a menu item is missing, check the current app rather than assuming the steps are identical in every release.

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Compress a PDF in SwifDoo on Android or iOS

  1. Open SwifDoo PDF and go to Tools > Compress.
  2. Select the PDF you want to compress.
  3. Choose a quality level. Select High Quality, Less Compression if preserving legibility is the priority; move to medium only if you need a smaller file and the first result is still too large.
  4. Tap Compress, then open and inspect the output.

SwifDoo’s Android and iOS guides say users who are not logged in can select a compression quality but cannot save or complete the compressed output. Check whether the current app requires sign-in for the operation. Follow the official Android guide or iOS guide if your screen differs.

Check that text and details remain readable

Do not judge the result by file size alone. Compare the compressed copy with the original at normal reading size, then zoom in on details that are easy to damage:

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  • tables, charts, and thin diagram lines;
  • signatures, stamps, and fine image detail;
  • scanned pages, especially small letters and faint lines.

For a scanned PDF, the page is image content. Selectable or searchable text is not proof that the scan itself remains clear. If details look blurred, jagged, or hard to distinguish, discard that output and try a higher-quality, less-compressive setting from the original. Do not compress an already compressed copy repeatedly if you can return to the untouched file.

If a document must meet an upload limit, compare the output’s size with that limit as well as checking legibility. The best setting depends on the PDF’s content and the intended use; there is no guaranteed reduction or universal setting that preserves every file.

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What compression does not do

SwifDoo documents separate tools for image optimization and searchable-PDF conversion in its Windows support guide: image optimization is under Convert > Image Converter, and searchable-PDF conversion is under Convert > To Searchable PDF. These are distinct functions; compression should not be assumed to perform OCR or to make every scanned page readable.

SwifDoo’s Android guide also describes PDF reflow, which adjusts layout, font size, and spacing for screen reading. Reflow changes how a document is presented; it cannot restore detail lost from a compressed page image. See the Android guide.

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How much smaller will the PDF become?

SwifDoo’s article updated May 15, 2026 reports a 40–60% reduction with medium compression in its own testing. It also describes one batch in which 30 PDFs totaling 850 MB were reduced to 210 MB in under three minutes on a “standard Windows laptop.” These are vendor-reported results, not independently verified benchmarks or a prediction for your file; the article does not provide an independently reviewable test protocol or specify the hardware and test files in detail. Your result depends on the PDF’s contents and the chosen setting.

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