How to use it
- Choose a Mode: Balanced for most PDFs, Strong for scanned documents.
- Pick a Compression level: Less, Recommended or More.
- Press Choose files or drop one or more PDFs. Compression starts straight away, and the list shows the new size and the saving for each file.
- Press Download for each file, or save them all as a ZIP. Changed the settings? Press Apply to all again.
Why some PDFs are so big
Text on its own takes little space. The weight usually comes from pictures: photos placed at full camera resolution, and scanned pages, where every page is one large image. An image's file size grows with its pixel dimensions and colour depth.
Fonts add weight too. A guide to PDF file size notes that adding a single font may increase a file by 400–600 KB. Fonts are needed to show the text correctly, so this tool leaves them alone.
Balanced and Strong, exactly
Balanced finds the JPEG photos inside the PDF and saves each one again at a lower quality, shrinking it if it is bigger than the level's size limit. Everything else stays exactly as it was: text, fonts, drawings, links, bookmarks and form fields. Photos under 20 KB are skipped as not worth it, and a photo is only replaced if the new version is at least 10 % smaller. CMYK print images and unusual colour types are left untouched so their colours can't shift.
Strong draws every page as a picture and builds a new PDF from those pictures, with the same page sizes.
| Level | Balanced | Strong |
|---|---|---|
| Less | Photos at JPEG quality 75, longest side at most 2600 px | Pages drawn at 200 DPI, JPEG quality 75 |
| Recommended | Quality 60, longest side at most 2000 px | 150 DPI, quality 65 |
| More | Quality 45, longest side at most 1400 px | 100 DPI, quality 55 |
For example, Balanced at Recommended turns a 4000 × 3000 photo into 2000 × 1500, a quarter of the pixels. Strong turns an A4 page into an image of about 1654 × 2339 pixels at Less, 1240 × 1754 at Recommended and 827 × 1169 at More.
What Strong mode costs you
Because every page becomes a picture, the new PDF loses everything that isn't visible ink:
- Text can no longer be selected, searched or copied, and screen readers can't read it aloud.
- Links and fillable form fields are gone.
- Bookmarks aren't kept.
- Small print in a PDF made on a computer can look softer, especially at More.
For a scanned contract, which was already a picture of each page, that's a fair trade. For a digital report or a form, use Balanced. Either way, keep your original.
When a PDF won't get much smaller
A PDF of plain text with few pictures is already compact, so there's little to remove. Balanced only changes JPEG photos, so a file whose weight is fonts, drawings or images stored another way barely changes. Scans that were already saved at low quality leave little room too.
In every case the result is compared with your file. If it isn't smaller, you get your original back with a note saying so, never a bigger file. If Balanced finds no photos at all, it only tidies the file's internal structure and tells you.
Upload limits and your original
Upload forms often state a limit such as 2 MB or 10 MB. The results list shows each new size, so you can check it against the limit before you send. If one try isn't enough, use More, or Strong for scans.
The compressed copy is named with "-compressed" added: invoice.pdf becomes invoice-compressed.pdf. Your original file isn't changed, and it never leaves your device. How the privacy works.
Questions
- Will compressing remove pages or change the page size?
- No. Both modes keep every page at its original size. Balanced changes only the photos; Strong replaces each page with a picture of it.
- Which mode is best for a scanned document?
- Strong at Recommended. Open the result and zoom in on the smallest text; if it's hard to read, run it again at Less.
- Will a digitally signed PDF stay valid?
- No. Both modes save a changed file, and a signature shows as invalid once the version it covers has been altered. Send signed documents as they are.
- Why does it say only the file structure was tidied up?
- Balanced found no JPEG photos it could shrink safely. If the PDF is a scan, try Strong.
- Can I compress a password-protected PDF?
- No. The tool will say the file is password-protected. Remove the password in the app that made it, then try again.
- Can I compress photos instead of a PDF?
- Yes, with the image compressor, which can also make each photo smaller than a size you set.