Shrink a PDF on Windows: browser or offline program

Without installation or offline: choose your route first

If you want to shrink a PDF on Windows, you usually face three questions, and you should answer each one separately. First: are you allowed to install software on this computer? Second: where should the file be processed? Third: do you have an internet connection while you work? The browser and an installed program answer these questions differently.

The browser route needs no installation. When you use compress PDF in the browser, your browser reads the selected PDF and processes it on your computer. The document content is not uploaded to a server for compression. However, the page loads the components for processing and preview from the network only when they're needed. This applies even if the page is already open. Without a connection, the process can therefore fail, and the browser route is not intended as an offline solution.

According to the manufacturer, an installed desktop program such as PDF24 Creator also works without internet. However, you must be allowed to install it. The guide on processing without upload explains exactly how browser-local processing differs from genuine offline operation.

On a public or shared computer

On computers at the Jobcenter, in a library or at a managed workstation, installing software is often blocked. In that case, the browser is the obvious route. Keep in mind, though, that when you download the shrunk PDF, it ends up as a file on this computer, usually in the Downloads folder or on a shared drive. “Reset” and “Edit a new file” only clear the selection on the page. They do not affect downloaded files, your original or synced copies.

• Choose your own storage location, such as your USB stick, if the browser asks for one when downloading.
• Upload or send the file while you're still at the computer.
• Afterwards, delete the downloaded PDF and any scans you stored on the computer, and empty the Recycle Bin if necessary.
• Sign out of any accounts you used for sending.

Process and save the PDF in the browser

The browser route consists of a few steps on the home page. The last step is the important one: you check the downloaded file, not the preview on the page.

1. Click “Choose PDF” and select the original file. Each file can be up to 50 MiB, which is 52,428,800 bytes.
2. Under “Method”, choose a mode. “Lossless optimization” reorganizes the internal structure without deliberately reducing image quality. “Balanced” and “Smaller file” can additionally re-save suitable images as JPEG, which may cost image quality.
3. If the recipient specifies a maximum size, use “Set target size”. Enter the value in exactly the unit the recipient specifies.
4. Start with “Compress PDF”.
5. Compare “Original” and “Result” in the preview. Read the exact values under “Original (bytes)”, “Result (bytes)” and “Saved (bytes)”.
6. Download the new PDF. Your original remains unchanged.
7. Open the saved file again. At the same zoom level, check all pages, small print and stamps. Also test the functions that matter to you, such as text search, form fields or links.

After processing, the tool automatically checks whether the result is a valid PDF and whether the number of pages, form fields and links is correct. However, only the saved file can show you whether everything looks right and works. If the tool doesn't find a valid smaller version, you get the original back, and “Saved (bytes)” shows 0. The guide PDF does not get smaller explains what you can do then.

The compressor rejects some files before changing them: digitally signed or certified PDFs, encrypted PDFs and files with a faulty structure. A scanned signature, by contrast, is just an image on the page and not a digital signature.

Does the saved file meet the limit?

What counts is the exact size of the saved file in bytes. Compare it with the limit in exactly the unit the recipient specifies. Rounded MB figures aren't enough for this. Also, a completed compression doesn't mean the target size was reached. “Set target size” counts a result as reached if it is no larger than the converted byte limit. If the recipient explicitly requires a file under the limit, it must be at least one byte smaller.

If the unit isn't clearly stated, the safest option is to use the smaller limit. If several requirements apply, for example to individual files, to the total size and to the number of files, you can check them together with check recipient limits. However, the recipient's system decides whether the file is ultimately accepted.

On Windows, you can also look up the exact byte size of a saved file in PowerShell. Change to the file's folder and enter (Get-Item -LiteralPath '.\bewerbung.pdf').Length, replacing the file name with the name of your file. The output property Length is described in the Microsoft documentation on Get-Item.

PDF24 Creator as a documented offline alternative

If you have to work without an internet connection or regularly edit PDFs on your own computer, an installed offline program is an option. One example is PDF24 Creator. It is a standalone product from another provider and not part of this website. When accessed on 13 October 2026, the official PDF24 Creator download page stated the following:

• Downloads are available for Windows 10 and Windows 11. According to the manufacturer, the program does not support Mac or Linux.
• The current version is listed as 11.31.1, dated 8 October 2026.
• According to the manufacturer, the program can compress and merge PDFs on the desktop without an internet connection.

The manufacturer describes the following installation process: wait until the installer has finished downloading. Then open the downloaded file, follow the setup and launch the program via the icon on the desktop. Whether you are allowed to install programs on a work, school or public computer is decided by whoever operates that computer.

According to the manufacturer's website (as of 13 October 2026), there are no costs: PDF24 Creator is described there as free of charge, including for commercial use. For the version, range of features, terms and the individual steps within the program, rely on the information on the download page at the time of your download. You check the saved result the same way as with the browser route: open the file, check all pages and the functions you need, and compare the exact byte size with the limit.

Merge several files, then shrink them

Do you need a single file in the end, for example your cover letter, CV and certificates for a job application? Then merge the PDFs first and shrink the finished document afterwards. That way, you check the size and content of exactly the file you submit. In the browser, you use two separate tools one after the other for this. The merged result is not automatically passed on for compression.

1. Open merge PDFs beforehand and select the files. Ordinary PDFs are supported. Each file can be up to 50 MiB, and all selected files together can total at most 100 MiB and 250 pages.
2. Set the PDF order before you merge.
3. Save the merged PDF.
4. Open the saved file and check the page count and order. Watch for a missing page, something that appears twice or a document in the wrong place.
5. Open the home page to compress and select the saved file there via “Choose PDF”. For this step, it may be at most 50 MiB.
6. Compress the file, download the result and check it completely once more, including the page count.

Which files the merge tool rejects

The merge tool deliberately accepts only ordinary PDFs. It rejects files with interactive form fields, digitally signed or certified PDFs and encrypted PDFs. This also applies to PDF portfolios and to files with embedded files or optional layers. Such documents are not silently converted into flat pages, because that conversion could remove fields, signatures or other functions that the recipient may need.

Not every completed form is an interactive form. A scanned form filled in by hand consists only of ordinary page content. The guide on PDFs with signatures and forms explains how to handle genuine digital signatures and form fields.

If the merged file is larger than 50 MiB

Merging can produce a file over 50 MiB that you can't select on the home page. In that case, go back to the unchanged source files. If they contain pages that the recipient doesn't require and that nobody else needs either, remove those pages from the relevant source file with delete PDF pages before merging. That tool accepts ordinary PDFs up to 50 MiB. You can also shrink the individual source files on the home page and then merge the shrunk versions. Whether the new result is then at most 50 MiB depends on the content. So after each step, check the saved file for completeness, order and exact byte size.

ZIP and printing are different processes

Windows offers several functions that sound like shrinking but produce something else. What matters is the result you end up with: a ZIP archive, a newly generated PDF or an optimized PDF.

ZIP archive: packaged, but not a smaller PDF

According to Microsoft's help on zipping and unzipping, the ZIP function in Windows 10 and Windows 11 creates a new ZIP archive in the same location. When you unzip it, you get the contained files back. The PDF itself is not optimized in the process. Microsoft also points out that image files that are already compressed hardly shrink any further. A portal that requires a PDF does not receive the required format if you give it a ZIP file. You can only find out whether a recipient accepts ZIP archives from their requirements.

NTFS compression: only saves space on the drive

Windows can store files and folders on NTFS drives in a space-saving way. The Microsoft documentation on the compact command also lists this storage compression for Windows 10 and 11. It only changes how much space the file occupies on your storage device. The PDF you upload or attach still has the same size in bytes.

Printing to PDF: a rebuilt document

If you output a PDF as a PDF again via a PDF printer, the result is a rebuilt document. It can be smaller, the same size or even larger, so a size reduction is not guaranteed. Links, form fields and digital signatures may be lost in the process. Text may also behave differently when you search or copy it. Older instructions with menu steps and printer resolutions may not match your current version of Windows. So check a file created this way completely before you send it.