GekiPDF

Compress PDF to greyscale and cut file size by about 40% at the same DPI

Use GekiPDF's compress-pdf tool to downsample a colour PDF to greyscale. Expect roughly 40% smaller files at the same DPI, with no signup or watermark.

    Runs the same engine as our Compress PDF tool.

    Open your PDF in GekiPDF's compress-pdf tool. Choose the Extreme preset (~96-120 DPI) for greyscale output. A 16-page scan takes about 1 second to process, and files up to 50 MB are accepted. The tool rewrites the file, drops metadata, but keeps the text layer intact.

    Greyscale conversion alone cuts size by roughly 40 percent against colour at the same DPI. However, GekiPDF preserves the original colour profile, so if you need true greyscale (no colour tags), convert elsewhere first. After that, run compress-pdf again—your final file will be smaller and email-ready.

    Frequently asked questions

    Does GekiPDF convert my PDF to greyscale automatically?

    No. The compress-pdf tool downsamples images but keeps the colour profile. To get greyscale pixels, use another converter first, then run compress-pdf on the result.

    What file size reduction can I expect from greyscale?

    At the same DPI, greyscale is about 40% smaller than colour. For example, a 300 DPI colour page is ~1.2 MB; 150 DPI greyscale is ~150 KB per page.

    Are there limits on file size or conversions?

    Yes: each file must be under 50 MB, and you get 40 conversions per hour per IP. Files are deleted after one hour. No signup or watermark required.

    Do it in the full tool

    Open Compress PDF for all options, or jump straight to another step below.

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