Free Online Engineering Tools

Compress PDF

Shrink a PDF to an exact size — 100 KB, 200 KB or any target you name. Images inside the document are recompressed while text stays selectable, and your file is never uploaded: completely private, instant, and free.

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Compress
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Drop your PDF here

or click to browse · PDF files · scanned documents compress best

Converts on your device — your PDF is never uploaded
pages
images
original
images are
Compression method Smart
Smart recompresses the images inside your PDF and leaves text and vector graphics untouched — so text stays selectable and searchable.
How much
Target file size 200 KB
The tool tries several quality and resolution combinations and keeps the best result that fits under your limit.
Extra saving
Convert images to grayscale
Useful for scanned text documents — often cuts another 20–40% with no loss of readability.
BEFORE Original
document.pdf
File size
Pages
AFTER Compressed
document-compressed.pdf
File size
Reduction
Text
✓ Saved to your device as document-compressed.pdf

Compress PDF — Hit an Exact Size, Keep Your Text

Shrink a PDF to an exact size limit — 100 KB, 200 KB, 1 MB or whatever a form demands. The default Smart mode recompresses the images inside your document and leaves text and vector graphics completely untouched, so the text stays selectable and searchable. Everything runs in your browser: no upload, no watermark, no sign-up, no daily limit.

It tells you what it can do before you press anything. As soon as you add a PDF it reports how much of the file is actually images. If images are 90% of it, expect a dramatic reduction. If they are 5%, no compressor on earth will do much — and you deserve to know that up front rather than after a disappointing download.

Why PDFs Get So Large

Almost always, it is images. A page of text is a few kilobytes: characters, positions and a font reference. A photograph or a scan of that same page is a grid of millions of pixels — often several megabytes.

Phone cameras made this worse. A photographed document at 12 megapixels carries about forty times more data than an office scanner produced twenty years ago, while upload limits stayed exactly where they were. That is the whole problem, and it is why compression targets images rather than text.

Smart or Maximum?

 Smart (default)Maximum
What it changesOnly the embedded imagesRe-renders whole pages
Text afterwardsSelectable & searchableFlattened to pixels
Works on text-only PDFsVery little to gainYes
Typical reduction (scans)60–90%Often more
Layout & vectorsUntouchedRasterised

Start with Smart. It is the right answer for the files people actually need to compress — scanned applications, photographed contracts, image-heavy reports — and it costs you nothing in text quality. Switch to Maximum only when Smart cannot reach your target, or when the PDF has no recompressible images at all (the tool detects that case and says so).

Measured Results

From testing on a 1.1 MB scanned-style document, using Smart mode with the structure and text preserved throughout:

SettingResultReductionLooks like
Quality 80, max 2000 px455 KB59%Indistinguishable
Quality 70, max 1600 px263 KB76%Excellent on screen and in print
Quality 50, max 1200 px123 KB89%Fine on screen, softer in print
Quality 30, max 800 px47 KB96%Visibly compressed — last resort

Your own results depend on what is in the file. These figures are a realistic guide rather than a promise, which is why the tool always shows you the actual before-and-after rather than a percentage claim.

Meeting a Specific Limit

Target mode does the trial-and-error for you. Enter a limit — or tap 100 KB, 200 KB, 500 KB, 1 MB, 2 MB — and the tool works through progressively stronger settings, stopping at the first one that fits so you keep the best quality available within your budget.

WhereTypical limitSet target to
Government & visa portals100–500 KB100 KB / 200 KB
University applications1–2 MB1 MB
Job application systems2–5 MB2 MB
Email (Gmail / Outlook.com)25 MB / 20 MB10 MB

Grayscale: the Overlooked Trick

If you are compressing a scanned text document, switch grayscale on. A colour scan stores three channels of data for what is essentially black ink on white paper — and the colour information is carrying nothing but scanner noise and paper tint. Converting to grayscale typically removes another 20–40% with no loss of readability at all.

Leave it off for anything where colour carries meaning: photographs, charts, highlighted text, stamps, signatures in blue ink.

What Compresses Well — and What Does Not

Type of PDFExpectWhy
Scanned documents70–90% smallerEntirely images, usually at needless resolution
Photographed pages from a phone80–95% smallerEnormous camera images inside
Reports with photos and charts40–80% smallerMixed content; images dominate the size
Text-only documentsA few percentNothing large to compress
Already-compressed PDFsLittle or nothingThe saving was already taken

If a file is already optimised, the tool says so rather than handing you a “compressed” copy that is the same size or larger. Nothing is ever made bigger: each image is only replaced if the new version is genuinely smaller.

Is It Safe and Private?

Yes, and you can verify it: load this page, disconnect from the internet, and compress a PDF. It still works, because the document is parsed and rebuilt by your own browser. No upload, no account, no watermark, and no copy of your file on anyone else’s server — which matters when the document is a passport scan, a bank statement or a signed contract.

Troubleshooting

“No recompressible images found”

Your PDF is text or vector based, so Smart mode has nothing to work on. The tool switches to Maximum automatically — but understand the trade: it will shrink the file by flattening pages into images, and the text will no longer be selectable.

The compressed file is barely smaller

Check the “images are” figure shown when you add the file. If images are a small share of the total, the size is coming from fonts, vectors or embedded data, and image compression cannot reach it.

It could not reach my target

Try grayscale, then Maximum mode. If it still will not fit, the document genuinely has more content than the limit allows — splitting it into two files is often the practical answer.

The PDF is password-protected

Open it in a viewer with the password, save an unprotected copy, then compress that.

Related tools: Need to combine files? Merge PDF. Compress PDF to 100 KB · to 200 KB · to 1 MB · Reduce PDF file size · to 500 KB · to 2 MB · Scanned PDFs · For email · JPG to PDF

Frequently Asked Questions

How do I compress a PDF?

Drop your PDF onto the upload area, choose a target size such as 100 KB or 200 KB (or pick a quality level yourself), then press Compress. The tool recompresses the images inside your PDF and shows a before-and-after comparison before you download. Everything happens in your browser - nothing is uploaded.

Will the text still be selectable and searchable?

Yes, in Smart mode, which is the default. It recompresses only the embedded images and leaves text and vector graphics completely untouched, so you can still select, search and copy text afterwards. Maximum mode is different: it re-renders whole pages as images, which compresses further but turns text into pixels.

Can I compress a PDF to exactly 100 KB or 200 KB?

Yes. Choose Target size, enter or tap the limit, and the tool works through progressively stronger settings until the file fits, keeping the best quality that does. It reports the size achieved, and tells you plainly if the target is not reachable.

Why did my PDF barely get smaller?

Because most of its size is not images. A PDF built from text, fonts and vector graphics has very little for an image compressor to work on. The tool shows you what percentage of your file is images as soon as you add it, so you know what to expect before pressing anything.

Is my PDF uploaded to a server?

No. The file is parsed and rebuilt entirely inside your browser. It is never uploaded, never stored and never seen by anyone - which matters, because the PDFs people need to compress are usually applications, contracts, statements and scans.

How much smaller will my PDF get?

For scanned and image-heavy PDFs, 60-90% is typical. In testing on a 1.1 MB scanned-style document, moderate settings gave 263 KB (76% smaller) and stronger settings 123 KB (89% smaller), with the page structure and text intact throughout.

What is the difference between Smart and Maximum modes?

Smart recompresses the JPEG images embedded in the PDF and leaves everything else alone, so text stays selectable. Maximum re-renders every page as a flat image: it shrinks any PDF, including text-only ones, but the result is a picture of your document. Use Smart first and switch only if you must go smaller.

Does grayscale help?

A lot, for scanned text. Colour scans carry three channels of data for what is essentially black ink on white paper. Converting to grayscale often removes another 20-40% with no loss of readability.

Will compression reduce quality?

Images are re-encoded, so yes - that is where the saving comes from. At moderate settings the difference is hard to see on screen. In Smart mode text and vector graphics are not touched at all, so they stay perfectly sharp no matter how hard the images are compressed.

Is there a file size limit?

No artificial limit. Because processing happens on your device, memory is the only real constraint. Very large scanned documents of several hundred pages may be slow on a phone.

Can I compress a password-protected PDF?

Not directly. Open it in a PDF viewer with the password, save an unprotected copy, then compress that. No legitimate tool should bypass document encryption.

Does it work offline?

Yes, once the page has loaded. Nothing is transmitted, so the compression itself needs no connection.