Compress a PDF to under 5 MB
Long scans, slide decks and reports under 5 MB, compressed only as much as needed, on your own device.
- Nothing is uploaded
- Works offline after first visit
- Open source
- No watermark · limit is your device’s memory; phones hold less
Makes a PDF smaller until it fits under 5 MB, trying a lossless cleanup first, then lighter image compression, and turning pages into pictures only if nothing else is enough. It is free, and your PDF is not uploaded: it is rewritten in your browser. The size limit is your device’s memory (phones hold less), and after one visit and a short wait the page works offline.
Done
Open the network tab. Your files never appear in it.
Add files and run the tool to see every request this tab makes.
Your files are processed on this device and never sent to a server. Reload the page to clear everything from memory.
Five megabytes is roomy for a typed document and tight for a scan. A phone scan of one page is usually 1 to 3 MB, so a 20-page scan is 20 to 60 MB and has to lose most of its weight. The useful way to think about it is the budget per page: 5 MB over 10 pages is 500 KB each, over 25 pages 200 KB, over 50 pages 100 KB and over 100 pages 50 KB.
The page works down a fixed ladder and stops at the first step that fits. It starts with a lossless rewrite, then recompresses the images at quality 75 and 2400 pixels, then at 60 and 1600, 45 and 1200, and 30 and 900. Only after those does it turn pages into pictures, at 150, 110 and 90 DPI, then 72 and 60 DPI in grayscale. The result card names the step.
For example, a 20-page scanned lease of 38 MB has to lose about 87 percent. At 250 KB a page there is a lot of room, so one of the image steps is the likely stop and no page has to be flattened. The card then reads like "under 5 MB: images at quality 60, 1600 px".
A PDF that is already under 5 MB is left alone, and the card says "already under 5 MB, original kept". The compressed file keeps the original file name, so save it in another folder or rename it.
How it works
- Drop the PDF or several.
- Keep 5 MB, or type the limit the upload form gives.
- Press Compress to 5 MB and read the result card for the step used.
In your browser, not on a server
Lossless cleanup rewrites the PDF with pdf-lib using compressed object streams. Image recompression uses pdf.js to find embedded images, re-encodes each one at a lower quality on a canvas, and pdf-lib swaps the new streams in. Flatten renders every page to an image at the resolution you pick. Each mode runs entirely in your browser.
Compared with upload-based tools: PDF compressors online are the most upload-hungry tools there are, because the whole document has to go up before anything happens. Here a 50 MB scan is processed without a single byte leaving your machine.
Verify it yourself. Give the page a short while after one visit to save itself for offline use, then turn off Wi-Fi or switch to airplane mode and run the tool again. Or open your browser's developer tools (F12, or Cmd-Option-I on a Mac), pick the Network tab, and watch it while you convert. The panel above does the same count for you.
Questions
Is 5 MB here the same as 5 MB on the upload form?
The page counts a megabyte as 1,000,000 bytes, so a result under 5 MB is at most 5,000,000 bytes. That is also under 5 MiB, 5,242,880 bytes, so it passes whichever way the form counts.
It says it could not get under 5 MB. What now?
The card then shows the smallest size it reached and suggests splitting. A hundred pages of colour scans is the usual cause. Split the PDF into parts with the split tool and compress each part.
Can I fit several PDFs into one 5 MB upload?
Combine them first with the merge tool, then compress the combined file here, so the whole bundle is fitted to the limit in one go. Compressing each file separately to 5 MB would leave you with more than 5 MB in total.
Will the text stay selectable?
Through the lossless step and all the image steps, yes. Only when pages are turned into pictures does the text become part of the picture, and the card says so. Typed documents almost always fit before that.
My PDF is 4 MB, so why compress it?
You do not need to: it is already under the limit and the card says original kept. If a form still rejects it, the limit is probably lower than 5 MB, so type the right number in the size box.
Is my PDF uploaded to be compressed?
No. The file is opened and rewritten by code running in this tab. Contracts and statements do not leave your device, and the result is saved straight to your disk.
More PDF tools
Compress PDF
Shrink a PDF for email or an upload limit. Pick a level, or type the size you need, like 1 MB, and the page tries the gentlest setting that fits. Processed on your device.
Remove PDF metadata
See the name, software and dates hidden in a PDF, and strip them before it goes out.
Grayscale PDF
Every colour becomes its own shade of grey, and the text stays text.
Crop PDF
Cut PDF pages down to what matters: draw the area to keep, or trim the white margins automatically.
Other conversions
Guides
- How to compress a PDF without losing qualityWhere the size comes from, which reductions are free, and where the quality trade-off actually starts.
- Is Smallpdf safe?Smallpdf is a reputable Swiss company with published retention rules. What changes the answer for you is which of its storage rules applies to your file.
- Is PDF24 safe?PDF24 is a long-standing German project, and it tells you itself that its offline app is the more private option. Here is how to choose between the two, and a third way.
- A free Smallpdf alternative with no daily limitSmallpdf's free plan has daily limits. Here is what that means, and a way around it where your files are never uploaded.
- A free iLovePDF alternative with no task limits or adsiLovePDF's free plan works, but with limits on documents, batches and file size. Here is what changes with a tool that never uploads the file at all.