Compress PDF
Shrink PDF file size by downsampling and recompressing images. Runs in your browser.
About this compress pdf
This tool makes PDF files smaller by shrinking the images inside them, right in your browser. It's for anyone who hits an email limit, an upload cap on a job or visa portal, or just a full phone.
Most oversized PDFs are big because of photos and scans, not text. The tool finds every image, works out how large it actually appears on the page, and lowers its resolution to the level you pick. Then it recompresses it as JPEG and tidies up the file structure. Text and vector drawings are never turned into pictures, so they stay sharp.
You see page 1 before and after, side by side, and you can zoom to 100% to check fine print. If the new file isn't smaller, you get your original back. Nothing is uploaded, which matters when the PDF is a payslip or a medical report.
Features
Three presets plus custom
Low keeps images at 220 dpi and 85% quality. Recommended uses 150 dpi and 72%. Extreme goes to 96 dpi and 50%. Custom lets you set any resolution from 50 to 300 dpi and any quality from 30 to 95%.
Downsampling based on real placement
The tool reads each page's drawing commands to see how big every image is printed, including images inside nested page objects. A 4000 px photo shown 2 inches wide is reduced; the same photo shown full page keeps more pixels.
Lossless cleanup
It merges identical images and fonts stored more than once, drops objects nothing refers to, compresses uncompressed streams, and saves with compact object streams.
Optional extras
Remove metadata and app-private data (some design apps store a whole editable copy inside the PDF), page thumbnails and attached files. Grayscale turns color photos and scans gray.
Honest before and after
You get both file sizes, how many images were changed, which were left alone and why. If the result is larger, the download is your original file.
How to use the compress pdf
- 1Choose a PDF. A sample with large photos is loaded to try first.
- 2Pick Low, Recommended or Extreme, or set your own dpi and quality.
- 3Click Compress PDF, compare the pages, then download the smaller file.
When to use it
Email attachments
Many mail services cap attachments at about 20 to 25 MB. A scanned contract or a photo-heavy report usually drops well under that on Recommended.
Portal uploads with tiny limits
Government and university forms often want files under 1 or 2 MB. Try Extreme, check the preview, and if it's still too big, split the PDF into parts and upload them separately.
Phone scans
Scanner apps save pages at high resolution and high JPEG quality. Recommended typically cuts these by half or more while keeping text readable.
Combined documents
After you merge several PDFs, the same logo or font may be stored many times. The duplicate pass keeps one copy.
Why is my PDF so large?
Almost always it's images. A phone photo is 12 megapixels or more, and a PDF keeps every pixel even when the photo is shown the size of a business card. A page scanned at 600 dpi in color holds about 35 million pixels.
Here's the math the tool uses. A 4000 × 3000 photo placed 6 inches wide is effectively 667 dpi. At 150 dpi it only needs 900 × 675 pixels, about one twentieth of the original. That's where big savings come from.
Other causes are smaller: fonts embedded in full, the same image stored on every page, old revisions left in the file after edits, and hidden data such as thumbnails or attachments.
How much smaller will it get?
It depends on what's inside. These are measured results from our own test files, not promises:
- A 6-page report with six 6-megapixel photos (13 MB): 1.2 MB on Low, 287 KB on Recommended, 85 KB on Extreme.
- Four color pages scanned at 300 dpi as JPEG (900 KB): 495 KB on Low, 227 KB on Recommended.
- A 42-page technical manual with diagrams and screenshots (6.5 MB): 3.5 MB, about 46% smaller.
- A 7-page text-only manual (165 KB): no saving, so the original was kept.
What this tool can't shrink
Some files are already as small as they reasonably get, and it's better you know before you try ten settings.
- Text and vector graphics. They're stored as instructions, not pixels. Fonts aren't re-subset, so a file that embeds large full fonts keeps them.
- Images in JPEG 2000, JBIG2 or CCITT fax format, 1-bit black-and-white scans, and images with a custom color mapping. These are left untouched.
- CMYK images, common in print-ready PDFs. Converting them safely needs color management that browsers don't offer.
- Files that are already optimized, such as a PDF compressed here before. Recompressing a JPEG at the same size only adds blur, so the tool skips images it can't shrink by at least 10%.
How to reduce PDF size without losing quality
Start with Low or Recommended and look at the zoomed preview. Screens show about 100 to 150 pixels per inch, so 150 dpi looks sharp on a monitor and prints fine on an office printer. Keep 200 dpi or more for anything you'll print professionally.
For scanned text, a lower dpi hurts small print first. If footnotes start to smear, go up a step instead of raising JPEG quality.
Why use Mavros
| Mavros | Typical upload sites | |
|---|---|---|
| Where the file goes | Stays in your browser | Uploaded to a server |
| Compression levels | 3 presets plus custom dpi and quality | 2 or 3 presets, stronger ones often paid |
| Before and after preview | Side by side, zoom to 100% | Usually none |
| Larger result | Original kept automatically | You download a bigger file |
| Limits | Your device's memory only | Daily task or file size caps |
Tips
- Compress once, from the original. Each JPEG round adds a little blur.
- If you plan to run OCR on a scan, do that before compressing. OCR reads sharper images more accurately.
- Building a PDF from photos? Shrink the photos first and the PDF starts small.
- Removing metadata also drops the document title and author. Untick it if you need them.
Questions
Is it safe to compress a PDF here?
Yes. The PDF is processed inside your browser and never uploaded. The page can't see your other files, and closing the tab clears everything from memory.
Does compressing a PDF reduce quality?
It can reduce image quality, never text. Text and vector shapes are copied as they are. Images get fewer pixels and stronger JPEG compression, so check the zoomed preview before you download.
Which compression level should I choose?
Recommended suits most people. It keeps images at 150 dpi, sharp on screens and fine for office printing. Use Low for print jobs and Extreme only when a strict size limit matters more than photo detail.
Why did my PDF barely get smaller?
It probably has few images, or its images are in formats left untouched, such as CMYK or JBIG2. Text-heavy PDFs are already compact. The summary under the result lists exactly what was skipped and why.
How do I compress a PDF to under 1 MB?
Try Extreme first, then Custom with a lower dpi such as 72. If it's still too big, split it into parts. A 30-page color scan rarely fits in 1 MB and stays readable.
Can I compress a password-protected PDF?
Not directly. Remove the protection first with the password remover, compress, and add a password again afterwards if you need one.
Does it work on a phone?
Yes, in any modern mobile browser. Very large files with many photos can run out of memory on older phones, so a laptop is better for files over 100 MB.
Will links, bookmarks and form fields still work?
Yes. Only image data and unused objects change. Links, bookmarks, form fields and the page order stay as they were.