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Compress PDF: Reduce PDF Size, Shrink PDF File Size and Make a PDF Smaller

Pick how much image quality to keep, see exactly how many KB you saved, and download the smaller file

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Text and vector drawings are never downsampled, so they stay sharp and selectable at every level. The saving comes from the pictures, which is why a scanned document shrinks far more than a text one.

Compressing a PDF makes it smaller by downsampling and re-encoding the images inside it. Text and vector graphics are left alone, which is why the result depends almost entirely on what the document is made of: a scanned file typically loses 50 to 86 percent of its size, while a text based PDF gives back roughly 20 to 25 percent almost regardless of which setting you pick. Upload the file above, choose a level, and the exact saving is shown before you download.

Last updated: August 2026

How much smaller does a PDF actually get?

Most compression pages quote a percentage without saying what they compressed, which is useless, because the answer swings from about 20 percent to 86 percent depending on the document. These are real files, run through this exact tool on the live site rather than on a developer machine, at the two levels people actually pick.

Document What is inside it Original Balanced, 150 dpi Smallest, 72 dpi
8 page scan at 200 dpi Page images only, no live text 3.88 MB 1.87 MB (down 52%) 546 KB (down 86%)
IRS Publication 15, 59 pages Live text and vector tables 1.63 MB 1.29 MB (down 21%) 1.23 MB (down 25%)
IRS Form 1040, fillable Form fields and line art 215 KB 130 KB (down 40%) 130 KB (down 40%)
IRS Form W-9, fillable Form fields and line art 137 KB 85 KB (down 38%) 85 KB (down 38%)

Scans give back the most

A scanned page is a photograph of paper, so every pixel is stored. Cutting it from 200 dpi to 72 dpi throws away roughly nine tenths of those pixels and the file follows. This is the case where compression genuinely solves the problem.

Text barely moves, at any level

The 59 page publication moved from 21 percent to 25 percent when forced from 150 dpi down to 72 dpi, which is almost nothing for a fourfold drop in image resolution. With no real photographs to downsample, the saving comes from font subsetting and stream recompression instead.

The two forms are a warning, not a win

Form 1040 lost 40 percent of its size, and part of that was the interactive form layer being discarded rather than any picture getting smaller. A saving on a file with no real photographs in it usually means something was thrown away. That is why this tool warns you first.

What compression keeps, and what it quietly removes

Every compressor rebuilds the document rather than editing it in place, and parts of the original do not make the journey. Here is what happens to each layer, measured on the files above rather than assumed.

Part of the file What happens What to do about it
Selectable text Kept. Still searchable and copyable at every level. Nothing. Text is not pixels, so it is never downsampled.
Photos and scanned pages Downsampled to the level you chose and re-encoded as JPEG. This is lossy and cannot be undone. Keep your original. Compress a copy, never your only version.
Fillable form fields Dropped. Form 1040 went from 199 interactive fields to none, and the page still looks identical. Fill the form in first, then compress the completed copy.
Digital signatures Broken. A signature certifies the exact bytes of the file, and compression changes all of them. Never compress a signed document. Compress it before signing.
Bookmarks and internal links Kept, because no pages are added or removed. Page count is unchanged. Nothing.
Document metadata Largely rewritten. Author and creation details are often replaced by the compressor. If metadata matters, check it afterwards. View the PDF metadata
Password protection Blocks the job. An encrypted PDF cannot be rebuilt, so the upload is rejected with an explanation. Remove the password first, then compress.

Which compression level should you pick?

The only thing the level changes is the resolution of the images. Pick by what the file has to survive next, not by how small you want the number to be.

Smallest file

Images at 72 dpi

Screen resolution. Use it when the file only has to be read on a monitor or a phone and has to clear a hard attachment limit. Scanned paperwork stays legible but noticeably soft, and small print in a photographed page can blur.

Best for: email attachments, upload forms with a tight cap, archiving read-only copies.

Balanced

Images at 150 dpi

The setting most people want. It halved a 200 dpi scan while leaving the text on the page clearly readable, and it is still acceptable for an office printer. If you are not sure, start here and only go stronger if the result is still too big.

Best for: sharing scanned contracts and statements, client deliverables, general use.

Keep print quality

Images at 300 dpi

300 dpi is the normal floor for commercial printing, so this level only touches images above it. On a file that is already at or below 300 dpi it will save little or nothing, and that is the correct outcome rather than a failure.

Best for: anything going to a print shop, high resolution photography, portfolios.

Why some PDFs will not compress, and what to do instead

If a compressor gave you back almost the same file, it probably was not broken. There are four ordinary reasons, and each has a different fix.

1. The document is text, not scans

This is by far the most common reason. Fonts and vector lines are already tiny and compression has nothing to work on. Expect roughly 20 to 25 percent, and expect the level to barely matter. If the file still has to be smaller, the only real lever left is removing pages.

Remove the pages you do not need and the size drops roughly in proportion.

2. It has already been compressed

Running a file through a second time re-encodes images that are already lossy. You lose a little more quality for almost no saving, and sometimes the file grows. This tool checks for that and hands back your original rather than a worse, larger copy.

3. The images are already below the level you picked

Asking for 300 dpi on a file whose pictures are 200 dpi correctly does nothing to them. Some tools hide this by using a downsampling threshold that skips images close to the target, which is why an apparently strong preset can return a completely unchanged file. Drop a level and it will act.

4. The size is in embedded fonts or attachments

A file carrying dozens of fully embedded fonts, or another file attached inside it, is heavy for reasons no image setting will touch. Font subsetting recovers part of it automatically. Attachments have to be removed in a PDF editor.

How to make a PDF smaller on Windows, Mac and iPhone

Windows

Windows has no built in PDF compressor. File Explorer can zip the file, which makes the download smaller but does not change the PDF itself, so any upload form that checks the PDF size will still reject it. Adobe Acrobat Pro has a Reduce File Size command, but optimizing a PDF on the desktop is a paid feature: the free Acrobat Reader cannot compress at all. Adobe also runs a free web compressor, though it is usage limited and your file still goes to their servers. A browser tool avoids the install entirely.

Mac

Preview can do it: open the PDF, choose File then Export, and select the Reduce File Size Quartz filter. It is free and already installed. The catch is that it is a single fixed setting with no resolution control, it is widely reported to soften images more than most people expect, and on files that are already light it can produce a larger PDF than the one you started with.

iPhone and Android

Neither the iOS Files app nor the stock Android file manager can compress a PDF. The practical route on a phone is a browser tool, because it needs no install and no account. Open this page in Safari or Chrome, tap the upload area, pick the PDF from Files or Drive, choose a level, and save the result back.

A note on zipping instead of compressing

Zipping a PDF usually saves very little, because the streams inside a PDF are already compressed. Worse, a ZIP does not help with the case people usually need help with: an upload form that reads the size of the PDF itself. If something is rejecting your file for being too large, the PDF has to get smaller, not the container around it.

Why people need a PDF to be smaller

Almost every case comes down to a hard limit somebody else set, which is why an approximate answer is not good enough. You need to know the number you landed on.

Email attachment limits

Personal Gmail refuses attachments over 25 MB and switches them to a Drive link instead. The number that actually catches people is on the desktop mail client, which is often set far lower, and a bounce from the recipient side is the version you find out about a day late.

Filing and portal uploads

Government portals, court filing systems, lender document portals and insurance claim uploads all cap the file size, and the caps differ from one to the next. A scanned bundle is the usual thing that blows past them.

Accounting and bookkeeping records

Scanned receipts and statements pile up fast, and most accounting systems limit what you can attach to a transaction. Compressing scans before they go in keeps years of records manageable.

Course and LMS uploads

Learning platforms cap uploads per file, and a scanned reading pack or a slide deck full of images is exactly the thing that fails. Dropping images to 150 dpi usually clears it without students noticing.

Files people download from your site

A 30 MB brochure on a phone connection is a brochure nobody reads. Compressing the images is the cheapest speed improvement available on a document heavy site.

Long term storage

Scanned archives are usually stored at a resolution far above what anyone will ever read them at. Retention rules say keep the document, not keep every pixel of it.

The file size limits you are actually up against

Knowing the target before you compress saves a second attempt. These are published limits, taken from each provider rather than from other articles, and checked in August 2026.

Where the file is going Published limit The part people get caught by
Gmail, personal account 25 MB On a Google Workspace account the administrator sets the limit, so your colleague and your client may not have the same one.
Outlook desktop client 20 MB, or 10 MB on an Exchange account This client side cap is lower than the server will accept, so Outlook can refuse a file that the mail system would have delivered.
Exchange Online, server default 35 MB sending, configurable from 1 MB to 150 MB Encoding an attachment for email inflates it by roughly a third, so a 30 MB PDF is not a 30 MB message.
IRS Document Upload Tool 15 MB per file, up to 40 files There is a page limit as well as a size limit: a PDF may be at most 120 pages.
Federal court e-filing, CM/ECF No national limit. Each court sets its own. Published values range from 15 MB to 100 MB across districts, with 35 MB common. Check Court Information inside CM/ECF rather than assuming.

If a portal is not on this list, look for its own stated limit before compressing. Guessing low costs you image quality you did not have to give up.

Common questions about compressing a PDF

How do I make a PDF smaller?
Upload the PDF, pick a compression level and download the result. The saving comes almost entirely from the images inside the file: a scanned document usually drops by 50 to 86 percent, while a PDF that is mostly text has far less to give back and typically shrinks by around 20 to 25 percent, with the level making very little difference.
Why is my PDF still so big after compressing it?
Almost certainly because it is a text document rather than a scan. Compression works by downsampling and re-encoding pictures, and a text PDF has almost none. Measured on this tool, a 59 page IRS publication went from 1.63 MB to 1.29 MB, a 21 percent saving, and forcing the strongest level only took it to 1.23 MB. There were no large photographs to shrink, so there was nothing more to win.
Does compressing a PDF reduce quality?
It reduces image quality, and leaves text alone. Text and vector drawings stay sharp and selectable at any level because they are not pixels. Photos and scanned pages are downsampled to the resolution you pick, so at 72 dpi a scan is clearly softer on screen, while at 150 dpi most scanned paperwork still reads cleanly.
How do I compress a PDF to 200KB?
Start at the strongest level and check the result, because no tool can guarantee an exact target size. The final size depends on how many pages and images the document holds. If 72 dpi still leaves you above 200KB, the usual fix is to remove pages you do not need first, since fewer pages means proportionally fewer bytes.
Does compressing a PDF remove fillable form fields?
Yes. Rebuilding a PDF drops the interactive form layer, so a fillable form comes back as a flat page that looks identical but can no longer be typed into. We check for form fields on upload and warn you before you compress. If you still need to fill the form in, compress it after it has been completed and flattened, not before.
How do I make a PDF smaller for email?
Compress it at the balanced level first and check the result against your mail provider limit. Gmail rejects attachments over 25 MB, and many corporate mail servers are stricter. For a scanned document the balanced level is usually enough; if it is not, drop to the strongest level or split the file and send it in parts.
Is it safe to compress a PDF online?
It depends on the service. On this page the upload is deleted from the server as soon as the compressed file is built, and the result is deleted the moment you download it. Nothing is kept and no account is needed. For documents under a legal or contractual confidentiality duty, a desktop tool that never leaves your machine is still the safer choice.
How do I make a PDF smaller on Mac without extra software?
Open it in Preview, choose File then Export, and pick the Reduce File Size Quartz filter. It is built in and free, and Apple warns that the result may be lower quality than the original. The catch is that it is one fixed setting with no resolution control, and users widely report both heavy softening and, on already light files, a PDF that comes out larger than the one they started with. A tool that lets you choose the level gives a more predictable result.
Does compressing a PDF change the number of pages?
No. Compression only rewrites what is on the pages, so the page count, the order and the bookmarks all stay as they were. If you need fewer pages as well as fewer megabytes, that is a separate operation: remove the pages first, then compress what is left.

Before and after you compress a file

Compression is often one step in a longer job. If the file is too big because it holds pages you do not need, cutting them out first saves more than any quality setting will, and it costs nothing in sharpness. If you are about to send the document outside your organisation, it is worth checking what the file says about itself before it goes.

Compress the PDF, then do something with it

If the document is study material, training content or a set of course notes, the same file can become a quiz. Upload it once and get multiple choice questions with explanations, ready to share or export.

Turn a PDF into a quiz