How to compress a PDF
- Choose the PDF you want to make smaller.
- Pick a compression level. Start with Light if the file must stay searchable.
- Press Compress PDF and the smaller file downloads automatically.
Choosing the right level
The three levels work in genuinely different ways, and the right one depends on what the document is for.
Light
This rewrites the file's internal structure using object streams, which packs the document's data more efficiently without touching its content. Text stays selectable, images are untouched, and the result is visually identical to the original. Savings are modest and depend heavily on how the file was produced. A PDF exported from modern software may already be optimised, in which case there is little left to gain.
Medium and Strong
These render each page and store it as a JPEG image. That produces much larger savings, often well over half the original size, because scanned documents and image heavy files compress very well this way.
The trade off is real and worth understanding: once a page is an image, the text in it is no longer text. You cannot select it, search it, or copy from it, and screen readers cannot read it aloud. Choose these levels when the document is going to be looked at rather than worked with.
When compression will not help
If a PDF is mostly plain text generated by a word processor, it is probably already small and tightly packed. Light compression may save nothing at all, and the tool will tell you rather than handing back a file that is no smaller.
Large files are usually large because of photographs or scans. Those are the cases where image compression makes a dramatic difference.
Accessibility worth considering
Converting pages to images removes the text layer that screen readers rely on. If the document will be read by someone using assistive technology, or needs to meet accessibility requirements, use Light compression and keep the text intact.
Frequently asked questions
Why did my file barely get smaller?
Light compression only reorganises the file structure and cannot shrink content that is already efficiently stored. PDFs exported from modern software are often already optimised. Try Medium or Strong if a larger saving matters more than keeping text selectable.
Will compressing make my text blurry?
Light compression does not change appearance at all. Medium and Strong convert pages to images, so text is rendered rather than stored as text and can look slightly softer, particularly at Strong.
Can I still search the text after compressing?
Only with Light compression. Medium and Strong turn pages into images, which removes the text layer, so searching, selecting and copying no longer work.
What is the largest file I can compress?
Up to 150MB. Because everything runs in your browser, very large files depend on your device having enough memory, and compressing them may take a little time.
Is my file sent to a server?
No. Compression happens entirely on your device and no copy of your document is uploaded.