How do I compress a PDF?
To compress a PDF, upload it to FixDoks's Compress PDF tool, pick a compression level or a target size in KB, then click Compress PDF. Photos and scans are resampled while text stays sharp. Your file is uploaded over HTTPS and deleted from the server as soon as the compressed PDF is returned.
Compress PDF at a glance
| Input | PDF, up to 50 MB |
|---|---|
| Output | Compressed PDF |
| Processing | On our server over HTTPS; files are deleted right after conversion |
| Max file size | 50 MB per file |
| Price | Free, no watermark |
| Download | Free Google sign-in |
| Works on | Chrome, Edge, Safari and Firefox on Windows, Mac, Android and iPhone |
How to use Compress PDF
- Click Select PDF files and pick one or more PDFs.
- Choose a Compression level, or switch to Target file size and enter the size in KB you need.
- Click Compress PDF, check the new size, and download.
Why do PDFs get so big?
Almost all the weight in a large PDF comes from images: scanned pages, phone photos of documents, and pictures pasted into Word or PowerPoint. A single page scanned in colour at 600 dpi can be several MB, yet it looks identical on screen at a fraction of that resolution. FixDoks compresses a PDF by lowering the resolution of oversized images, re-encoding them efficiently, removing duplicate images, subsetting fonts and rebuilding the file structure. Text and vector drawings are left untouched, so they stay perfectly sharp.
Choose a compression level
| Level | Image resolution | Best for |
|---|---|---|
| Light | about 220 dpi | Documents you will print, brochures with photos |
| Recommended | about 150 dpi | Email attachments, office uploads, sharing on WhatsApp |
| Strong | about 96 dpi | The smallest file for strict upload limits; photos get softer |
Tick grayscale as well if colour does not matter (for example a scanned certificate or ID). Removing colour can cut the size further.
Compress to an exact size in KB
Government and exam portals, scholarship sites, job applications and visa forms often reject a PDF that is over a limit such as 100 KB, 200 KB, 500 KB or 1 MB. Switch to Target file size, type the limit, and FixDoks tries several settings on the server and returns the best-quality version that fits under your target. If the target is impossible without making the pages unreadable, you get the smallest version we could make and a message saying so. Quick presets: 100 KB, 200 KB, 500 KB and 1 MB.
How much smaller will it get?
It depends entirely on what is inside. A scanned PDF or one full of photos often shrinks by 70 to 90%. A PDF that is mostly text, like a report exported from Word, is already small and may only shrink a little. If compressing would make your file larger, which can happen with PDFs that are already optimised, FixDoks returns your original file unchanged instead.
Tips for very large files
- Scanning again at 150 or 200 dpi in black and white or grayscale gives far smaller PDFs than colour at 600 dpi.
- If you only need some pages, remove the rest first with Remove PDF Pages.
- Making a PDF from photos? Build it with JPG to PDF, then compress it here.
Privacy
Compressing on a phone
Many people hit a size limit while filling a form on their phone. This page works in mobile Chrome and Safari: tap Select PDF files, pick the document from Files or Downloads, choose a level or a target size, and download the smaller PDF straight into your downloads folder. WhatsApp also accepts larger documents than email, but a smaller file sends faster on a slow connection and is easier for the recipient to open.
Compression runs on our server so it can use Ghostscript, the same engine professional print shops use. Your PDF is processed in a private temporary folder and deleted immediately after the compressed file is returned.