What Compress PDF changes inside the PDF
Try this when an email or portal says the PDF is too large.
The file is rewritten in the browser. Some PDFs shrink. A scan made of large photos often stays almost the same size, because the pictures are not resampled.
Where this falls short
If the size barely changes, export the pages to JPG, compress the images, and build a new PDF with JPG to PDF. Do not expect a 20 MB scan to become 200 KB here.
A related step, if you still need one, is Merge PDF.
Compress PDF without the extra promises
Compress PDF sits on this site because PDF and PDF are not interchangeable, even when they look similar in a file list. Try this when an email or portal says the PDF is too large. Application portals, email, and print shops still ask for PDF in 2026, often with a size cap. Application portals, email, and print shops still ask for PDF in 2026, often with a size cap.
The file is rewritten in the browser. Some PDFs shrink. A scan made of large photos often stays almost the same size, because the pictures are not resampled.
Read this about PDF before you upload
PDF keeps a page looking stable on most screens. It is the file offices send when the reader should not casually reflow the layout. A scan or a photo of a page has no text layer until OCR runs, and OCR is only as good as the image.
Keep the PDF if anyone might need the original page look, because extracts drop columns and images.
Read this about PDF before you send the download
Compress PDF keeps the format family as PDF and still changes the file you can use. Application portals, email, and print shops still ask for PDF in 2026, often with a size cap. A PDF exported from Word or a browser usually has a text layer, so the words can be copied.
Converting a PDF does not improve a blurry scan, and a text extract is not the designed page.
Keep, check, then delete
People lose time when they convert before they know which rule failed. Size, pixel dimensions, codec, font encoding, and layout are different rules. Compress PDF only addresses the PDF to PDF step. Try this when an email or portal says the PDF is too large. The file is rewritten in the browser. Some PDFs shrink. A scan made of large photos often stays almost the same size, because the pictures are not resampled. If the size barely changes, export the pages to JPG, compress the images, and build a new PDF with JPG to PDF. Do not expect a 20 MB scan to become 200 KB here. The file stays in your browser and is not uploaded. The limit is 100 MB. Keep the original until the download has been opened in the program that will use it. Do the test with a short or simple file first when the real file is large. A one-page PDF, a single photo, or a one-minute clip will show you whether the output is the kind of file you needed. After that test looks right, run the real file once. Keep both the PDF original and the PDF download until the receiving person or the upload form accepts it. A PDF page can be text, a scan, or a picture of a design. Compress PDF does one of those jobs, not all of them. If you needed editable sentences, a text extract is the right family. If you needed the page to look identical, send the PDF or export from the app that built it. Open the download before you throw away the original.
Here is the decision for Compress PDF. You start with PDF and you stop when a real program accepts PDF. A PDF exported from Word or a browser usually has a text layer, so the words can be copied. A scan or a photo of a page has no text layer until OCR runs, and OCR is only as good as the image. If those two sentences describe a tradeoff you do not want, do not convert. Renaming the extension by hand will not do this job. Running the tool twice on its own output will not do it either.
If the size barely changes, export the pages to JPG, compress the images, and build a new PDF with JPG to PDF. Do not expect a 20 MB scan to become 200 KB here.
A related step, if you still need one, is Merge PDF.
Other jobs start from the homepage, where each tool is named for the conversion it actually does.