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How to compress a PDF
To compress a PDF, open it here, pick a preset and press Compress PDF. The tool shows the original and new size side by side, so you can try another preset before you download anything.
- Choose the file or drop it on the box. A small preview of page 1 appears, and the tool counts how many pages are mostly pictures.
- Pick Smallest, Balanced or High quality. Each one is just a DPI and JPG quality pair, and you can change both numbers yourself.
- If an upload form has a limit, type it in Maximum size (or tap 500 KB, 1 MB or 2 MB). The tool then lowers the settings in steps, up to six passes, until the file fits.
- Press Compress PDF, check the result, then download.
Why a scanned PDF is huge and a Word PDF is not
A PDF saved from Word stores text as text, which takes a few KB per page. A scan stores each page as a photo, and a 300 DPI colour scan of an A4 sheet is easily 1 MB on its own. A 10-page scan can pass 10 MB without anyone noticing.
That is where this tool works. It finds the pages where pictures cover about a third of the page or more, draws each one again at the DPI you chose and saves it as a JPG. Pages made of real text are copied untouched, so they stay small and searchable. If nothing in the file is a picture, you get your original back and a message saying so. Shrinking a text PDF by turning it into pictures would usually make it bigger.
Which preset should I use?
DPI is the number of pixels per inch of paper. More pixels mean sharper text and a bigger file.
| Setting | A4 page becomes | Good for |
|---|---|---|
| Smallest, 72 DPI, JPG 50% | 595 × 842 px | Tight size limits, large print, forms you only need to read on a phone |
| Balanced, 110 DPI, JPG 70% | 910 × 1286 px | Most letters, forms and ID scans |
| High quality, 150 DPI, JPG 85% | 1240 × 1754 px | Small print, certificates, contracts, anything printed again |
In our test file (three noisy full-page scans, 3.29 MB), Smallest gave 94 KB, Balanced 454 KB and High quality 1.94 MB. Your file will land differently, because clean black-on-white pages compress far better than photos. Try Balanced first. Go down only if the limit forces you, because 72 DPI makes 9-point text soft.
How do I compress a PDF to 1 MB or 2 MB?
Set the maximum size and let the tool find the settings. The number of pages decides whether this is realistic:
| Pages | Budget per page at 1 MB | Budget per page at 2 MB |
|---|---|---|
| 1 | 1024 KB | 2048 KB |
| 5 | 205 KB | 410 KB |
| 10 | 102 KB | 205 KB |
| 20 | 51 KB | 102 KB |
A readable scanned page usually needs somewhere around 50 to 150 KB, so 20 pages in 1 MB is a stretch. If the tool cannot reach your limit it still gives you the smallest result and says how far off it is. Then you have two real options: use Page range to send only the pages that are required, or turn on Grayscale.
Compress only some pages
Choose Page range and type something like 1-3, 5, 8-. Here 8- means page 8 to the end. Pages outside the range can stay exactly as they are or be left out. Leaving them out is the quick way to make a 40-page file into the 4 pages somebody asked for.
What you lose, honestly
- Re-rendered pages become pictures. You cannot select or search their text any more. For a scan this changes nothing, since it was a picture to begin with.
- Bookmarks and form fields are not carried over to the new file.
- Sharpness is limited by the DPI you pick. You cannot get back detail that was thrown away, so keep the original.
- Password-protected files can be opened here with the password, but all their pages are re-rendered.
The new file is never allowed to be larger. When the result would not be smaller, the tool returns your original file and tells you.
Is it safe for ID scans and contracts?
The PDF is read and rebuilt inside your browser tab. The only things downloaded are the pdf.js and pdf-lib code, and they are loaded once. Nothing you open is sent anywhere, which matters for passports, ID cards and signed contracts.
Frequently asked questions
How do I compress a PDF to 1 MB?
Open the PDF, type 1 MB in the maximum size box (or tap the 1 MB chip) and press Compress PDF. The tool tries your chosen preset first, then lowers the resolution and JPG quality step by step, up to six passes, until the file is under 1 MB. If even the lowest setting is too big, it tells you the smallest size it reached.
How do I compress a PDF to 200 KB?
Type 200 in the maximum size box, switch on Grayscale if colour is not needed, and compress. A one-page scan usually gets there. A 10-page scan will not, because 200 KB leaves about 20 KB per page, which is below what a readable page needs. Compress only the pages you must send.
Why did my PDF not get smaller?
Most likely it contains text and vector graphics only, such as a file exported from Word or Excel. Those pages are already compact, so the tool leaves them alone and returns your original file. Only pages where pictures cover about a third of the area or more are re-rendered.
Will I lose quality or the ability to select text?
On pages that are re-rendered, yes: each page becomes a JPG picture, so text can no longer be selected or searched, and sharpness depends on the DPI you choose. For a scan this changes nothing, since a scan was a picture already. Pages with real text are copied untouched.
What is the best setting for a scanned document?
Balanced (110 DPI, JPG 70%) is a good start for forms and letters. Use High quality (150 DPI) when the text is small, such as a certificate or a contract, and Smallest (72 DPI) only when the size limit is tight and you can accept softer text.
Can I compress only some pages of a PDF?
Yes. Choose Page range and type something like 1-3, 5, 8-. The other pages are either kept exactly as they are or left out of the new file, whichever you pick. Leaving them out also makes the file smaller.
Can the compressed file be bigger than the original?
No. If the new file would be the same size or larger, the tool says so and gives you the original back instead. This happens with PDFs that were already compressed hard, or low-resolution scans.
Is my PDF uploaded to a server?
No. Pages are drawn and re-encoded in your browser with pdf.js and pdf-lib, and the result is built in memory. After the page and PDF engine have loaded, it keeps working offline.