This free PDF compressor reduces the size of a PDF right inside your browser, so you can email it, attach it to a form, or upload it to a portal without hitting a size limit. Drop in a file, pick how hard to compress it, and download the smaller version. There is nothing to install and no account to create, and your document is never sent to our server — the whole job happens on your own device.
Drag & drop your PDF files here
or choose files from your device
PDF only • Up to 100 MB per file • Up to 20 files per session
Your PDF is read and rewritten inside this browser tab and is not uploaded to our server. The only files the page fetches are the two open-source JavaScript libraries that do the compression.
A PDF gets heavy for predictable reasons: photos and scans embedded at full camera resolution, fonts repeated on every page, and bookkeeping data the creating program left behind. None of that changes what the document says, which is why a PDF compressor is one of the few tools people reach for without worrying about the content. This page is a free online PDF compressor built for that single job — reducing the file size of a PDF so it fits somewhere it currently does not.
Everything runs in the browser tab. There is no upload step, no queue, no waiting for a server to finish, and no account. If you need a hard target rather than a general reduction, the size-specific versions of this tool are listed further down the page.
PDFs are the default container for documents that must look identical everywhere, and that reliability comes with a cost: they preserve layout, fonts and images exactly, so they grow quickly. A few pages of text can stay tiny, but the moment a report includes screenshots, a scanned contract, or a photo-heavy brochure, the file size jumps into tens of megabytes.
Common situations where that becomes a problem:
Email providers cap attachment sizes, government and university portals cap uploads, and cloud storage plans are sold by capacity. A smaller PDF clears all three without changing a word of the document. If the limit you are up against is a specific number rather than "smaller, please", it is easier to aim at that number directly — for example with our compressor that targets a 500KB upload limit.
How do I compress a PDF online?
Drop the PDF into the box at the top of this page, choose a compression level, and press Compress PDF. The file is rewritten on your own device, and when it finishes you get the original size, the new size, the measured percentage change, and a download button.
Reducing a file size means removing data, so there is always a trade-off — the only question is whether the trade-off is visible. Light mode makes the safe trade: it rewrites how the PDF is stored and drops information that was never shown on a page, while leaving the page content itself alone. Text stays sharp and selectable, and images are untouched. What you get depends on how wasteful the original file was.
Balanced and Strong make the visible trade instead: each page is re-rendered as an image, so the document is rebuilt from pictures rather than text and vectors. That is where the dramatic reductions come from on scanned paperwork and photo-heavy reports, and it is also where fine print starts to soften and the text layer disappears.
How much a particular PDF can shrink depends on:
Realistic expectation: a scan-heavy PDF often shrinks by a large margin, while a document that is already well optimised may only lose a few per cent. No compressor can promise a fixed percentage, because the starting point is different for every file.
Different tools take different routes. This one uses two, and the level you pick decides which is used.
A PDF is not a single continuous document; it is a collection of objects with a table telling the reader where each one lives. That table is often stored uncompressed, and the file can carry metadata such as the author's name, the program that produced it and the original creation date. Light mode rebuilds the file with compressed object streams and, if you leave the metadata option ticked, writes it back without the identifying details. Embedded images and fonts are copied exactly as they were, which is why the text stays selectable and the appearance does not change.
These levels take a completely different approach. Each page is drawn at a chosen resolution, saved as a JPEG, and placed into a brand-new PDF. Because a compressed image is far lighter than the combination of fonts, vectors and embedded pictures it replaced, the result is usually much smaller — especially for scans. The cost is that the page is now a picture: the text cannot be selected, searched or copied, and links, form fields and bookmarks do not carry over.
Neither route changes what a reader sees at a glance. What changes is how much information is stored behind that appearance.
Three levels are enough to cover almost every situation. If you are unsure, start with Light and move up only if the file is still too large.
| Level | What it does | Best for | What you give up |
|---|---|---|---|
| Light | Rewrites the PDF structure with compressed object streams; optionally removes metadata. | Contracts, invoices, reports and anything you may need to search or copy later. | Nothing visible. Savings are modest on files that were already optimised. |
| Balanced | Re-renders each page as a high-quality image (around 150 DPI) and builds a new PDF. | Scanned documents, photo-heavy brochures, and portals with a strict upload limit. | Selectable text, links, form fields and bookmarks. Very small print may soften. |
| Strong | The same rebuild at a lower resolution and image quality (around 100 DPI). | Thumbnails, previews, and documents where the size limit matters more than sharpness. | Everything Balanced gives up, plus noticeable softness on detailed pages. |
If your target is a fixed number of kilobytes rather than a general reduction, work backwards from the limit instead: the 200KB PDF compressor handles the tightest limits, while a roomier allowance is better served by the 2MB version of this tool.
Compressing is rarely a goal in itself — it is what you do when something refuses your file. The usual triggers:
There are also times when compression is the wrong tool. If what you actually need is an editable file, run the document through our PDF to Word converter instead. If you need the pages as pictures for a presentation or a website, extracting PDF pages as JPG images is the more direct route. And if the page dimensions are the problem rather than the byte count, the Resize PDF tool changes the page size itself.
Email is where most PDFs get stuck. Mailboxes are sold with a total capacity, attachments travel through servers that enforce their own maximum message size, and a scanned ten-page document can easily exceed it. A smaller PDF also sends faster and is less likely to be rejected by the recipient's mail server before it ever arrives.
If a message keeps failing, compress the PDF first and check the new size before attaching it again. For documents that need to stay under a typical attachment allowance, the Compress PDF to 2MB tool aims at that figure directly. Sending one smaller file is also kinder than splitting a document across several emails, which is what most people end up doing otherwise.
Upload forms are stricter than email and less forgiving. A portal that accepts a document "up to 200KB" will reject a 400KB file outright, and many of them give no useful explanation beyond a generic error. The maximum is set by the organisation running the form, so the only practical answer is to bring the file under the limit before you upload it.
Check the form for the exact figure it asks for, then compress towards it. Portals with very tight limits are the reason we publish a dedicated Compress PDF to 200KB tool, and if the form is more generous, the 500KB PDF compressor keeps more of the original quality while still clearing the limit. Whichever you use, download the result and confirm the size shown in your file manager before submitting — the number in the tool and the number on the form are what matter.
The compressor works on Android phones, iPhones, iPads and Android tablets, in Chrome, Safari, Firefox and Edge. Nothing needs to be installed, and the page is built for touch: the buttons are large enough to tap comfortably and the layout does not scroll sideways on a narrow screen.
The one difference on a phone is how you add a file. Dragging and dropping is not available in most mobile browsers, so tap Choose PDF Files and pick the document from your device storage, Downloads, or a cloud drive that is connected to your phone. Large documents take longer to process on a phone than on a laptop, and a very big file can run out of the memory a mobile browser allows — if a large PDF fails, try again on a desktop browser.
This is where the design of the tool matters more than any promise. The compression here does not happen on a server: your PDF is read into the browser's memory, processed by JavaScript running on your own machine, and offered back to you as a download. Your document is never transmitted to us, so there is no copy on our side to store, log or delete. When you close the tab, the data in memory is gone.
Two details are worth stating plainly, because they are true of this page and often left unsaid elsewhere:
The advantage of this model is that it also works offline once the page has loaded, and it means you can compress a confidential document without handing it to a third party. If your file is protected by a password, however, we cannot help — see the limitations below.
Knowing the limits saves time, so here they are:
Most people arrive here with one specific limit to clear. These pages cover the neighbouring jobs:
If the document you are shrinking is actually a picture, the equivalent tools on the image side are the image compressor and the image resizer that targets 50KB. Browse everything else from the PDF tools hub.