Compress PDF and reduce file size, no upload
Pick a file and a compression level to see the size before and after. Your files never leave your device.
Last reviewed: October 31, 2026Runs in your browser. Nothing you enter or open is uploaded.
The short answer
Choose a PDF, pick light compression to keep the text selectable or strong compression for scanned files, then click Compress PDF. You see the size before and after and the percent saved, then download the smaller file. Everything runs in your browser, so the file is never uploaded to a server.
How it is calculated
Light: re-saves the JPEG photos inside the file at 70% quality (medium setting), shrinks images larger than 2000 pixels, and removes unused objects, thumbnails and metadata except the title. Text, links and fonts stay as they are.
Strong: draws each page as an image at 150 dpi (medium setting) and saves it as a JPEG in a new file with the same page size. Files get much smaller, but the text becomes part of the image and can no longer be selected or searched.
Percent saved = (1 − size after ÷ size before) × 100. If the file does not get at least 1% smaller, we keep your original and tell you.
Worked example
Sarah needs to send a scanned lease through a portal that takes files up to 5 MB:
- She picks the file, and the tool suggests strong compression because it is scanned.
- She leaves quality on medium and clicks Compress PDF.
- For example, if the file was 9.0 MB and becomes 2.7 MB, that is 70% smaller.
The file is now under 5 MB, and she downloads it with Download compressed PDF.
Quick reference table
| Your file | Best option | What to expect |
|---|---|---|
| Scanned document or phone photos | Strong | Usually a big drop; text becomes an image |
| Report or slides with many photos | Light, then strong if needed | Shrinks as much as the photos allow |
| Text-only file | Light | Small savings; it is often compressed already |
| You need to copy or search the text | Light only | Text stays selectable |
Special cases and common mistakes
- Password-protected PDFs cannot be compressed. Unlock the file first, then try again.
- If the file does not shrink, we say so and keep your original instead of handing you a bigger copy. This happens with text files that are already compressed.
- Strong mode turns pages into images, so links and fillable form fields stop working. Keep the original too.
- Very large files can take a while on a phone because all the work happens on your device. Keep the page open until it finishes.
Frequently asked questions
How do I reduce the size of a PDF?
Choose the file here, pick light or strong compression, click Compress PDF, then download the smaller copy.
Can I compress a PDF without uploading it?
Yes. Compression runs entirely in your browser and your files never leave your device. You can check by going offline after the page loads.
Will the text still be selectable?
Yes with light compression. Strong compression turns pages into images, so the text can no longer be selected or searched.
Why didn’t my PDF get smaller?
It is probably compressed already, or it is mostly text without large images. Try strong compression or a lower quality; if it still does not shrink, we keep your original.
Is it free?
Yes. No sign-up, no watermark and no limit on how many files you compress.
Sources
- pdf-lib: the open-source library that rebuilds the file in your browser (Last reviewed: October 31, 2026)
- PDF.js by Mozilla: draws the pages for strong compression (Last reviewed: October 31, 2026)