Why PDFs get so large
A PDF that is mostly typed text is usually small. Size grows when a document contains scanned pages or photos. A phone scan of a single page can be several megabytes, because it stores a detailed image of the paper. Documents exported from design programs can also carry large embedded images and fonts.
That becomes a problem when a university portal, job site or government form sets an upload limit, or when an email will not send. When you compress PDF files here, you get two honest ways to make them smaller.
Two compression modes
Basic: keeps text selectable
Basic mode rebuilds the PDF’s internal structure more efficiently and leaves out data that nothing uses. Your pages look exactly the same, and text can still be selected, copied and searched. It is the safe choice for contracts, reports and forms.
The savings are often modest, and a PDF that is already well optimized may not get smaller at all. When that happens, the tool says so and gives you back the original rather than a file that is no smaller.
Strong: for scanned documents
Strong mode redraws each page as a compressed JPEG image and builds a new PDF from those images. For scans and photo-heavy files, this usually makes a big difference. The trade-off is clearly shown before you start: text will no longer be selectable or searchable, because every page becomes a picture.
You can choose a quality preset: High (150 DPI) for sharp, readable pages, Medium (110 DPI) as a balance, or Low (72 DPI) for the smallest files that are still easy to read on screen.
Compressing to an exact size
Many forms ask for a PDF “under 200 KB” or “no more than 1 MB”. In Strong mode you can pick a target: 50 KB, 100 KB, 200 KB, 300 KB, 500 KB, 1 MB, 2 MB, or a custom size.
The tool then tries progressively lower image quality, and if that is not enough, lower resolution, until the file fits. It reports the real result. If the document has many pages, a very small target may not be reachable while keeping pages readable; in that case you see the smallest size achieved, so you can decide what to do next.
A useful rule: the more pages a document has, the more room it needs. A single scanned page can usually fit in 100 KB, while a twenty-page scan needs a larger allowance.
Tips for smaller PDFs
- Scan in black and white or grayscale when color does not matter.
- Remove pages you do not need. Use Merge PDF with page ranges to keep only the required pages, then compress the result.
- Starting from photos? Shrink them with Compress Image and then combine them with JPG to PDF; that often produces a smaller file than scanning to PDF directly.
- Check readability by opening the compressed file and zooming in before you submit it.
Private by design
Your PDF is processed in your browser, on your own phone or computer. It is not uploaded to our servers, so sensitive documents such as payslips, IDs or medical letters stay with you. There is no sign-up and no watermark.
Works on phones and computers
The tool runs in any up-to-date browser on iPhone, Android, Windows or Mac. Because your device does the work, Strong mode on a long document can take a little while on an older phone; a progress bar shows which page is being processed. Files over 100 MB or 300 pages trigger a warning so you know to expect a wait.
If you need individual pages as images rather than a smaller PDF, PDF to JPG converts them directly.