Compress PDF files until they fit the limit

Find out why the PDF is large first

Before you try to compress PDF files, it helps to know what is making yours heavy. Usually it is one of two things: big images inside the pages, such as scans or photos, or leftover material in the file that no page actually uses. The first is hard to avoid and shrinks a lot once you reduce the pictures. The second is small and easy to clean up.

A report saved straight from a word processor is mostly text, which is tiny, so there is not much to remove. A contract scanned on an office machine, a set of phone photos turned into a PDF, or slides exported as pictures carry a large image on every page. Those files can drop dramatically. Knowing which kind you have saves you from being surprised by the result.

Basic or Strong: which mode for which file

The tool offers two levels. ‘Basic’ repacks the file's structure, recompresses its data at the highest lossless setting and drops resources that no page uses. Text and pictures are left alone, so the document looks identical and stays searchable. The saving can be modest, though.

‘Strong’ redraws every page as a JPEG at about 144 dpi and quality 62, never more than 2,000 pixels on the long side, and assembles a new PDF with the same page sizes. Scans and picture-heavy files get much smaller. The price is that each page becomes an image, so you can no longer select, search or copy its text.

A simple rule works well. If you will need to copy or search the text later, start with ‘Basic’. If the file is already a scan, so the words are a picture anyway, or the limit is tight, go straight to ‘Strong’.

How to compress PDF files, step by step

The names below match the buttons on the page. Nothing needs installing and no account is involved.

• Press ‘Choose files’ and pick the PDF you want to shrink. If you forgot one, ‘Add more’ puts it in the same list, and ‘Clear’ lets you start over.
• Look for ‘Compression’ and choose ‘Basic’ for a document that is mostly text, or ‘Strong’ for a scan or a file built from photos.
• Press ‘Compress PDF’. Every file gets a row showing its original size, its new size and the percentage you saved.
• Take a single result with ‘Download’, or a batch with ‘Download all (ZIP)’. The icon on each row also saves just that file.
• If the size is still above your limit, switch to ‘Strong’ and press ‘Compress PDF’ again. Each run begins from your original, so an earlier attempt never lowers the quality of the next.

Email attachments and upload forms: what size to aim for

Mail services differ in how large an attachment they accept, and schools, offices and job portals often set their own cap for uploads. Check the instructions of whoever receives the file, then use that number as your target. The tool cannot aim for an exact size such as 1 MB; it shows what each of its two levels produced, and you decide if it fits.

Say you took ten photos of receipts and combined them into one PDF to send for an expense claim. ‘Basic’ may change almost nothing, because photos are already compressed. Switch to ‘Strong’, press the button again, and the new size on the row tells you straight away whether it is under the limit.

In the opposite case, a ten-page text report that is already small gains little from ‘Strong’ and loses its selectable text. For files like that, removing a few unneeded pages usually helps more than any compression.

What quality you lose, and what you keep

‘Basic’ costs nothing you can see, because the content is not re-encoded. What it removes is only unused material, so on screen or on paper you should not notice a difference.

‘Strong’ is a real trade. At 144 dpi a page reads comfortably on a screen, but fine print, thin lines in a drawing or a zoomed-in detail can look softer. The text is no longer selectable, and any hidden text layer from earlier recognition is gone as well.

Keep your original somewhere safe. The tool never changes your PDF; it creates a copy to download. That copy has the same file name, so store it in another folder or add a word such as ‘small’ to the name to avoid mixing the two up.

When the PDF will not get smaller

If ‘Basic’ barely moved the number, most of the file is probably images that are already compressed. Try ‘Strong’. If a row says the original was kept even then, the new file would have been larger, so the tool left it alone. That also tells you the file was already light.

Still over the limit? Send the document in two parts, since each half often fits. Dropping pages you do not need also helps. A password-protected PDF may fail to process, but the other files in the same batch carry on.

A last check before you send it

The files are processed inside your browser rather than uploaded, and the tool is free, with no sign-up and no watermark. That is reassuring for documents such as contracts or copies of ID.

Even so, open the result before sending. Look at the first and last pages and any page with a table or a stamp. If you compressed several files at once, remember that the names in the ZIP match your originals.