How to compress a PDF without losing quality
Updated · PDF Converter
“Without losing quality” means different things depending on what is inside your PDF. Text and vector graphics can be kept perfectly sharp at any compression level. Photos and scanned pages are where the savings – and the trade-offs – are. This guide explains what each level really does, so you can pick the one that makes the file smaller without any visible change.
Compress a PDF in three steps
- Open Compress PDF and drop in one or more PDFs.
- Under Compression, choose a level (see the table below). Recommended is selected by default.
- Press Compress PDF and download the result. Each file shows its size before and after, so you can see exactly what was saved.
What each compression level changes
| Level | What happens to images | Best for |
|---|---|---|
| Lossless | Nothing – only the file structure is optimised | Contracts, text documents, anything where not a single pixel may change |
| Light | Reduced to 300 dpi if stored higher, re-encoded at high quality | Files you will print |
| Recommended | Reduced to 150 dpi, re-encoded at good quality | Email, sharing, reading on screen |
| Strong | Reduced to 72 dpi, stronger compression | The smallest possible file for on-screen viewing |
At every level, text and vector graphics are never turned into images, and embedded fonts are kept as they are. Letters stay crisp at any zoom, and you can still select, copy and search the text.
Truly lossless: the Lossless level
If you need the document to look exactly the same, choose Lossless – restructure only, no quality change. This rewrites the PDF’s internal structure – removing duplicate data and storing objects more efficiently – without touching a single image.
The catch: savings depend on how the file was made. A bloated PDF exported from some programs can shrink noticeably, while a file that is already well built may barely change. If Lossless is not enough, move up to Light.
No visible loss: Light and Recommended
Most large PDFs are large because their images are stored at a much higher resolution than they are ever shown. A phone photo placed in a small box on a page may hold several times more pixels than the page can display. The tool measures how big each image actually appears on the page and reduces only the ones stored at a higher resolution than the chosen level needs.
- Light keeps print quality (300 dpi) and re-encodes images at high quality. In normal viewing and printing, differences are very rarely visible.
- Recommended (150 dpi) is plenty for reading on a monitor or phone. For typical documents with photos or scans, the difference is very hard to spot, while the file usually gets much smaller.
Images are only replaced when the new version is genuinely smaller, and every compressed file is re-opened and checked before you get it. If the file cannot be made smaller, you get your original back.
When you need it as small as possible: Strong
Strong brings images down to 72 dpi. That is fine for a quick preview or a slide deck viewed on screen, but photos will look soft when you zoom in and printing will show it. Text is still unaffected.
Tip: if you have to meet an upload limit, choose Target size instead and pick the limit, for example 1 MB. The tool tries gentle settings first and stops at the first one that fits, so you keep as much quality as the limit allows.
Other ways to make a PDF smaller without blurring it
- Remove pages you do not need. Blank scanner pages and cover sheets add size for nothing. Remove them with Delete Pages, then compress.
- Convert scans to black and white. A grey-scale scan of a text document is much smaller than a colour one. PDF to Black & White does this before you compress.
- Compress once, from the original. Each round of image compression loses a little more detail. Start from the original file rather than one that has already been compressed.
Is my file uploaded?
No. Compression runs inside your browser tab, so the PDF stays on your device – useful for payslips, contracts and medical documents.
Frequently asked questions
Can you compress a PDF without losing any quality at all?
Yes, with the Lossless level, which only optimises the file structure. How much smaller the file gets depends on how it was created; text-only files that are already compact may shrink very little.
Which compression level should I use for printing?
Light. It keeps images at print resolution (300 dpi) and only reduces images stored at a higher resolution than that.
Why did my PDF hardly get smaller?
Files that contain mostly text are already compact. The biggest savings come from PDFs with photos or scanned pages, because those images are what the higher levels reduce.