SantoshTec PDF

Compress a PDF and reduce its file size

Get an oversized PDF under an email or upload limit. Choose how aggressive to be, see the exact before-and-after size, and keep the file on your own computer throughout.

Drop the PDF you want to shrink

Nothing is uploaded — compression runs on this device.

    Compression method

    Lower resolution is the biggest single saving.
    Below 50 you will start to see blocky artefacts.
    Colour

    Heads up: Strong mode turns each page into a picture. The result looks the same but the text can no longer be selected, searched or copied. For scans that is no loss at all. For a text document, use Safe mode.

    Nothing is uploaded. This page opens and rewrites your PDF using your own browser's memory, then shows you the finished pages so you can check them before you download.

    Using Compress PDF, step by step

    1. Drop the oversized PDF onto the box above.
    2. Pick a method. Strong rebuilds every page as an image and gives the big reductions. Safe only rewrites the file structure and leaves text selectable.
    3. Adjust the quality slider if you need to hit a specific limit, then press Compress PDF.
    4. Check the before-and-after figures, open the result to confirm it still looks right, and download it.

    Where the bytes in a PDF actually are

    Before compressing anything it helps to know what you are compressing. In practice almost every oversized PDF is oversized for one of three reasons, and they call for different responses.

    Scanned pages. A phone photograph of an A4 sheet is often twelve megapixels — perhaps 3 MB per page before it even becomes a PDF. Reading that page needs a fraction of that detail. This is the case where Strong mode produces dramatic savings with no meaningful loss, because you are discarding resolution that was never useful.

    Embedded fonts. A PDF carries the fonts it uses so it renders identically everywhere. A full font family can be several hundred kilobytes. Well-made PDFs embed only the characters actually used; poorly made ones embed everything. You cannot fix this by compressing — you fix it at export time by subsetting fonts.

    Structural waste. Documents that have been edited repeatedly accumulate orphaned objects, superseded revisions and duplicated resources. This is exactly what Safe mode clears out, and it is why a file that has been through several rounds of edits often shrinks noticeably with no visible change at all.

    Choosing a resolution you will not regret

    Resolution matters more than JPEG quality. Halving the DPI removes three-quarters of the pixels; dropping quality from 80 to 70 removes perhaps a tenth of the bytes. If you need a big reduction, take it from resolution first and leave quality reasonably high.

    As rough guidance: 150 DPI is genuinely printable and is the safe default when a document may end up on paper. 120 DPI is comfortable on any screen and is where most people should start. 96 DPI is fine for reading but small footnotes begin to soften. 72 DPI should be reserved for documents that will only ever be glanced at on a screen.

    Greyscale deserves more attention than it usually gets. Most scanned documents are black text on white paper that a colour scanner has faithfully recorded in colour anyway. Converting to greyscale often halves the file again and, for that kind of document, removes nothing a reader would notice.

    Compress last, not first

    If your document still needs assembling, do the assembly first. Every compression pass is lossy, and running two of them costs you twice. The efficient order is merge, then organise, then number, and compress once at the very end against the actual limit you are trying to meet.

    One more thing worth checking before you compress: are all those pages necessary? Removing six blank scanner artefacts with delete pages is lossless, instant, and often gets you under the limit without touching image quality at all.

    Frequently asked questions

    How much smaller will my file get?

    It depends entirely on what is inside it. A scanned document — photographs of paper — commonly drops by 70 to 95 per cent, because camera and scanner images are wildly over-detailed for reading. A text-only PDF exported from Word may barely shrink at all, because there is almost nothing to remove. The tool shows you the exact before and after size, so you never have to guess.

    What is the difference between the Strong and Safe methods?

    Strong draws each page and re-saves it as a JPEG inside a new PDF. That is where large savings come from, but the page becomes a picture: the text is no longer selectable, searchable or copyable. Safe only rewrites the file's internal structure, removing redundancy and unused objects. It keeps everything selectable but typically saves only 5 to 20 per cent.

    Which should I choose?

    If the PDF is a scan, it was already just images — use Strong and lose nothing you had. If the PDF is a contract, a CV, or anything that will be searched, quoted or read by an automated system, use Safe, and if that is not enough, reduce the source images before exporting to PDF instead.

    I need to get under 2 MB for a government form. What settings?

    Start with Strong at 120 DPI and quality 70. Read the resulting size, and if it is still too large step down to 100 DPI, then 96. Turning on greyscale roughly halves the size again and is almost always acceptable for a scanned text document. Anything below about 96 DPI starts to make small print hard to read, so if you get there, consider splitting the document instead.

    Does compressing damage the original?

    No. Your original file is opened read-only and never modified. The compressed version is a brand new file that only exists once you press download. If you dislike the result, change the settings and run it again.

    Why did my file get bigger?

    Occasionally Strong mode enlarges an already well-optimised text PDF, because turning crisp vector text into a photograph of that text takes more bytes than the text did. When that happens the file was already efficient — use Safe mode, or accept the size.

    Related PDF tools

    Most jobs need two or three steps. These pair well with Compress PDF.