Compress PDF Online — Reduce PDF File Size up to 80%_
Shrink a scanned or image-heavy PDF for email and upload limits. Pick a level, compare the size before and after, and download — free, no upload, no watermark, no sign-up.
Guide — make a PDF smaller in three clicks
Drop it on the box or click to pick it. Its current size is shown at once.
Low keeps the most detail, Medium is the balanced default, High makes the smallest file.
Press Compress PDF. Each page is redrawn in turn; the progress bar counts them.
Two bars show the size before and after, with the saving in percent.
Save name_compressed.pdf, or pick another level and compress again. The original stays as it was.
What the levels do
Pages are redrawn at about 144 dpi with JPEG quality 88. Small text stays crisp when you zoom in. Choose it when the file only needs to shrink a little.
- For
- Reports with fine print, documents you may print
About 115 dpi at quality 72. Text reads normally on screen and photos look fine; the file usually ends up a fraction of a 300 dpi scan.
- For
- Email attachments, sharing, archiving scans
About 86 dpi at quality 52. Pages look softer when zoomed past 100%, but a typed letter is still easy to read at normal size.
- For
- Upload forms with a 1 or 2 MB limit
Every page is turned into a picture of itself. That is where the big saving comes from, and it is why the text can no longer be selected, searched or read aloud.
- Keep
- The original, if the text matters
- Instead
- Split a text PDF rather than compress it
Compress a PDF online, without uploading it
Compress PDF reduces the file size of a PDF in your browser, so it fits through an email attachment limit or an upload form. Pick one of three levels, see the size before and after, and download the smaller file. It is free, with no watermark, no account and no daily cap, and the document is never uploaded: compression runs on your own device.
Why PDFs get large
Nearly always because of images. A scanner or phone camera stores a full photo of every sheet, often at 300 dpi or more, so a ten-page scan can reach 20 MB while the same text exported from Word is under 200 KB. Photos, screenshots and charts in a report do the same. Fonts and text take up very little room.
How this compressor works
Each page is rendered with Mozilla's PDF.js at a lower resolution and saved as a JPEG, and the JPEGs are put back together into a new PDF with pdf-lib. A 300 dpi scan redrawn at about 115 dpi has around a seventh of the pixels, and JPEG compression shrinks those further. That is why scans and photo-heavy files often get 50–80% smaller.
| Level | Resolution | JPEG quality | Use it for |
|---|---|---|---|
| Low | ≈ 144 dpi | 88 | Fine print, possible printing |
| Medium | ≈ 115 dpi | 72 | Email and everyday sharing |
| High | ≈ 86 dpi | 52 | Strict upload limits |
What you give up
Because every page becomes an image, text stops being text. The document looks the same, but you can no longer select, copy or search it, and a screen reader cannot read it out. Links and form fields go too. Every compressor that gets this kind of saving on scans works the same way. If the text layer matters — for accessibility, a legal filing or someone who needs to search the document — keep the original or use one of the options below.
When compressing will not help
A PDF exported from Word, Google Docs or LaTeX is already compact: it is mostly text and vector shapes, with nothing heavy to throw away. Redrawing those pages as images can make the file barely smaller or even larger, and loses the sharp text. If such a file is too big, the cause is usually one or two embedded photos. In that case split the PDF into two parts that each fit, or remove the heavy pages with Rotate PDF, which keeps everything lossless.
Getting under a size limit
Gmail allows attachments up to 25 MB, Outlook.com up to 20 MB, and many company mail servers stop at 10 MB. Government portals and job sites often cap uploads at 1 or 2 MB. Start at Medium and look at the result. Still too big? Try High. Is it far under the limit? Go back to Low for a sharper file. Two tries are usually enough. No tool can promise an exact size in advance, because the result depends on what is on your pages. For a multi-page scan that must fit under 500 KB, split it into a few files and compress each part.
Scans with an OCR text layer
Some scanners and apps add a hidden text layer to a scan so you can search it. Compression removes that layer along with the rest of the text. If you need a scan that is both small and searchable, compress first and run OCR afterwards in a program that does both.
Signed documents
Do not compress a PDF that carries a digital signature. Any change to the file breaks the signature's validation, and compression rewrites every page. Send the signed original, or split it if it is too big for one email.
Private and free
Online compressors upload your document to their server. This one does all the work in your browser tab, so a payslip, contract or medical scan never leaves your computer or phone. Your original file is never changed; the compressed copy is a new download. For merging, splitting and converting, see the tabs above or the PDF tools page.