The two ways to resize a PDF

When you want to change a PDF's size, you have two separate choices, and they do different things. You can compress the file itself — making the document take up less storage space on your computer — or you can change how large it appears when you open it, which doesn't change the file at all. Most people need the second one. If your PDF looks too small or too large on your screen, you adjust the zoom. If you need to email it or upload it somewhere and the file is too big, you compress it.

The method you use depends on what program you have open the PDF in. A web browser, Adobe Reader, and a document editor like LibreOffice all have different controls. This guide covers the most common situations: zooming in a browser, zooming in Adobe Reader, and compressing a file before you send it.

Key Takeaways

  • Zooming changes how large the PDF appears on your screen but does not change the actual file size.
  • Most browsers let you zoom with Ctrl and the plus key (or Cmd and plus on Mac), and this setting stays until you change it again.
  • Adobe Reader has a zoom dropdown menu in the toolbar and also lets you fit the page to your window width.
  • Compressing a PDF reduces the file size for storage or sending, and most free tools online or in your document editor can do this in under a minute.
  • Compression trades image quality for file size, so test the result before you send it to someone else.

Zooming in your web browser

If you opened the PDF in Chrome, Firefox, Safari, or Edge, use the keyboard shortcut to zoom. Hold Ctrl and press the plus key to make it larger, or Ctrl and the minus key to make it smaller. On a Mac, use Cmd instead of Ctrl. Each press zooms in or out by about 10 percent.

The zoom level stays at whatever you set it to until you change it again — even if you close the tab and reopen the PDF later. If you want to reset it back to the original size, use Ctrl+0 (or Cmd+0 on Mac). You can also use the zoom controls in the browser menu: look for a magnifying glass icon in the top right corner of the window, click it, and select your zoom percentage from the dropdown.

Zooming in Adobe Reader

Adobe Reader has a dedicated zoom menu in the toolbar at the top. Look for a dropdown that shows a percentage — usually "100%" by default — and click it to see your options. You can select a specific percentage, or choose Fit Page to make the entire page fit your window width, or Fit Width to stretch it across the full width of your screen.

The keyboard shortcuts work here too: Ctrl+plus and Ctrl+minus zoom in and out, and Ctrl+0 resets to 100 percent. If you use Adobe Reader regularly, the zoom level you set will stay the same the next time you open that same PDF file.

Compressing a PDF to reduce file size

If the PDF file itself is too large — usually because it contains high-resolution images — you need to compress it. This actually changes the file, making it smaller by reducing image quality slightly. Before you compress and send a PDF to someone, open the result and check that it still looks acceptable to you.

The easiest method is to use an online tool. Search for "compress PDF" in your browser, and you will find free websites like Smallpdf, ILovePDF, or PDF Compressor. Upload your file, choose a compression level (usually "medium" or "high"), read the result, and check it. This takes about two minutes and requires no software installation.

If you prefer not to upload files to a website, you can compress within a document editor. If you have LibreOffice installed, open the PDF in LibreOffice Draw, go to File menu, select Export as PDF, and in the dialog that opens, click Options. Check the box for Reduce image resolution and set it to 150 DPI (dots per inch) for a good balance between size and quality. Click Export and choose where to save the compressed version.

When compression is worth doing

Compression makes the most difference when your PDF contains photographs or scanned documents. A text-only PDF is usually already small and won't shrink much. If your file is under 5 MB, most email services and websites will accept it without compression. If it's between 5 and 25 MB, compression usually brings it down enough to send. Above 25 MB, you may need to split the PDF into separate files or ask the person receiving it whether they can accept a large file.

After you compress, the file size shrinks but the page dimensions stay the same — a compressed PDF still displays at the same zoom level as the original. Compression only affects how much space the file takes up on disk or how long it takes to upload.

Adjusting PDF display in document editors

If you opened the PDF in a document editor like LibreOffice Writer or Microsoft Word, the zoom controls are usually in the bottom right corner of the window. Look for a percentage with a plus and minus button next to it, or use the same keyboard shortcuts: Ctrl+plus and Ctrl+minus. Some editors also have a View menu where you can choose zoom options.

Keep in mind that opening a PDF in a word processor can sometimes change how it looks — fonts may shift, spacing may adjust, or images may move. If the PDF is important and needs to stay exactly as designed, open it in a browser or Adobe Reader instead of a document editor.

Frequently Asked Questions

Does zooming change the actual file size?

No. Zooming only changes how large the PDF appears on your screen. The file itself stays exactly the same size on your computer. If you zoom in, close the file, and reopen it, the zoom level you set will stay, but the file size does not change.

What's the difference between "Fit Page" and "Fit Width"?

Fit Page shrinks or enlarges the PDF so the entire page fits inside your window, which may leave blank space on the sides. Fit Width stretches the PDF so it fills the full width of your window, which usually means you have to scroll up and down to see the whole page. Use Fit Width if you want to read text comfortably without scrolling left and right.

Will compressing a PDF make it look blurry?

Compression reduces image quality slightly, but at medium compression levels, most people don't notice the difference on screen. Text stays sharp because it compresses differently than photos. If you compress at the highest level, images may look noticeably softer. Always open the compressed file and check it before sending it to someone else.

Can I undo compression if I don't like how it looks?

No — compression permanently removes image data, so you cannot get the original quality back from the compressed file. Always keep the original PDF, and compress a copy instead. That way, if the compressed version doesn't look good, you still have the original to try again with different settings.

Why is my PDF so large in the first place?

PDFs are usually large because they contain high-resolution images, scanned documents, or embedded fonts. Text alone takes very little space. If someone sent you a large PDF, they likely scanned a paper document at high quality, or created it from a design program that includes detailed images. Compression is the fastest fix.