How to reduce PDF size for upload: shrink the pictures inside the file. On an iPhone, export it from Preview with “Optimize Images for Screen” turned on; on a Mac, use Preview’s “Reduce File Size” filter; on Android or Windows, use an in-browser compressor. Then check the size against the portal’s limit and confirm every page is still readable.
Most “file too large” errors come from scanned certificates, IDs and photos of documents, the files people upload to job and school applications, tenders, and visa and government portals. Below are the tools already on your phone and computer, scanning settings that keep files small, and how to handle private documents safely.
How to reduce PDF size for upload: the quick answer by device
| Device | What to use |
|---|---|
| iPhone or iPad (iOS 26) | Preview: Export as PDF with smaller images |
| iPhone or iPad (iOS 16 and later) | Shortcuts: “Optimize File Size of PDF” |
| Mac | Preview: Quartz Filter “Reduce File Size” |
| Android | Rescan with Google Drive, or a browser tool |
| Windows | Re-export from the original file, or a browser tool |
Why some PDFs are so large
A PDF of typed text is usually small, because it stores letters and fonts rather than pictures. A scanned PDF is different. Each page is a photograph of paper, and a phone camera records far more detail than a portal needs to read a certificate. Colour adds weight, and so do large photos in a designed brochure or portfolio.
That tells you where to cut. Compression lowers the resolution of those page images and saves them as JPEG. If your PDF is mostly typed text and still too big, compressing will barely help. Removing pages, or exporting a fresh PDF from the original Word or Excel file, will do more.
Compress a PDF on your phone (iPhone and Android)
iPhone and iPad
From iOS 26 and iPadOS 26, Apple’s Preview app can save a smaller copy of a PDF. The steps in Apple’s Preview guide for iPhone are:
- Open the PDF in Preview and tap the Actions menu next to the file name.
- Tap Export and choose PDF as the format.
- Turn on Optimize Images for Screen, which lowers image resolution, and Save Images as JPEG.
- Tap Done, choose where to save, rename the file if you like, and tap Save.
The Shortcuts app also has an “Optimize File Size of PDF” action, added in iOS 16, which compresses the images inside a PDF. Neither route lets you choose how strong the compression is, so check the result.
Android
No single PDF compressor comes with every Android phone, because each brand ships its own apps. If the file is a scan you made yourself, the simplest fix is to scan it again with the Google Drive app. The Google Drive scanner lets you crop the page, apply a filter such as greyscale, and save the result as a PDF.
For a PDF someone sent you, open our free PDF Tools in Chrome or any phone browser, choose the Compress tab and pick a level: Balanced, Smallest file or Light. Black and white makes it smaller still. This works on an iPhone too.
Compress a PDF on a computer (Windows and Mac)
Mac
Open the PDF in Preview, choose File > Export, then pick Reduce File Size from the Quartz Filter menu. Type a new name in the Export As box so you keep the original. Apple notes that the compressed copy may be lower in quality than the original, so zoom in on the small print before you upload.
Windows
Windows does not include a dedicated PDF compressor. If the document began in Word or Excel, export a fresh PDF from that file instead of scanning a printout. For a scan, use PDF Tools in any browser. “Microsoft Print to PDF” is a virtual printer rather than a compressor, and results vary, so check the size before relying on it.
Can you reduce PDF size without losing quality?
Not entirely. Shrinking images always discards some detail, so the goal is no loss you can see at normal zoom. Three habits help:
- Start with a balanced setting and go stronger only if you are still over the limit.
- Compress once, from the original. Compressing a file that is already compressed blurs it further.
- Keep the original for printing later.
One trade-off to know about our Compress tool: it saves each page as a picture, so text in the new file can no longer be selected or searched. That is fine for a scanned certificate. For a CV or a typed proposal where the text should stay selectable, export from the source document instead.
Is it safe to compress PDF online? Uploading vs in-browser processing
Many online compressors upload your file to their servers, process it there and send it back. That means handing a copy of your passport or medical report to a company you may know nothing about. In March 2025, the FBI’s Denver field office warned that criminals were using free online file converters to deliver malware and to collect personal details, such as banking information and passwords, from the files people submitted.
In-browser processing works differently. When you use our in-browser PDF compressor, the work happens in the web browser on your own phone or computer, and the file is not sent to a server to be processed. There is no sign-up either.
Privacy checklist for IDs, certificates, medical and legal files
- Use the tools on your device, or an in-browser tool, for anything with your ID number, date of birth, bank details or health information.
- If you must use an upload service, read its privacy policy to see how long files are kept, and be wary of any converter that asks you to install software to get your result.
- Open tools from a site you typed in or bookmarked, not from a link in a message.
- Upload only what the portal asks for. If it wants the data page of your passport, do not send every page.
- For client files covered by professional confidentiality, such as a patient’s results or a legal brief, follow your organization’s or regulator’s rules before using any outside service.
Merge, split and reorder pages before you submit
Portals often want one file per requirement, such as all your certificates in one PDF. In PDF Tools you can:
- Merge PDF files in the order you set. Bookmarks and form fields from the originals are not kept.
- Reorder and rotate pages, and remove ones you do not need, such as a blank back side.
- Split and extract the pages you choose (for example 1-3, 5), save every page as its own PDF, or cut a long file into equal parts.
- Turn images into a PDF, so phone photos of a document become one file with one picture per page.
Do this before you compress. Merge, take out what the portal does not need, then compress the finished file once.
Scan smarter: settings that keep files small and readable
- Use greyscale or black and white for text. Keep colour only where it matters, such as a passport photo or a coloured stamp the reviewer must see.
- Pick a sensible resolution. Adobe recommends 300 dpi for greyscale or colour scans for the best results. For a page that only needs to be read on screen, try 150 to 200 dpi and check that small print is still clear.
- Crop to the page. The table top around a document adds size.
- Scan flat, in good light. Shadows and creases add speckles that do not compress well.
- Shrink photos before you combine them. If you photographed the pages, run them through the Image Compressor & Resizer first, then turn them into one PDF.
Fixing “file too large” errors on upload portals
Whether you need to compress a PDF to 2MB, 1MB or 500KB, the routine is the same:
- Read the limit on the portal itself. Limits and formats differ and can change yearly, so go by the official instructions.
- Check the current size. See the file’s info on your phone, Properties on Windows or Get Info on a Mac.
- Compress with a balanced setting first. If the file is still too big, choose the smallest setting and black and white.
- Remove what is not required. Blank pages, duplicates and extra documents the portal did not ask for all add size.
- Split if the portal allows several uploads. Two smaller files may be accepted where one large file is not.
- Match the format. If the portal wants a JPG rather than a PDF, save the pages as pictures with “PDF to images”, or set a “Must be under” size in KB in the Image Compressor.
- Open the result before you submit. Zoom in on names, dates, signatures and stamps. A file that fits but cannot be read can still cost you the application.
PDF Tools and the Image Compressor are two of the free business tools on this site, all of which run in your browser with no sign-up needed.
Frequently asked questions
How do I compress a PDF to 2MB?
Check the current size, then compress it in Preview on iPhone or Mac, or at the Balanced level in an in-browser tool such as our PDF Tools. If the file is still over 2MB, choose the smallest setting and black and white, remove pages the portal does not need, or split the file if several uploads are allowed.
Can I reduce PDF size without losing quality?
Not completely, because compression lowers the detail in the page images. What you can aim for is no loss you notice at normal zoom. Start with a balanced setting, compress once from the original file, keep that original, and export typed documents from Word or Excel instead of scanning a printout.
Is it safe to compress PDF online?
It depends on the service. Many online compressors upload your file to their servers, and in 2025 the FBI warned that criminals were using free online converters to spread malware. For IDs, certificates, medical or legal files, use the tools built into your phone or computer, or an in-browser tool that processes the file on your device.
How do I compress a PDF on my phone?
On an iPhone or iPad with iOS 26 or iPadOS 26, open the PDF in Preview, tap Export, choose PDF and turn on Optimize Images for Screen. On Android, scan the document again in Google Drive with a greyscale filter, or open an in-browser PDF compressor in Chrome and choose a level.
