Change the File Size of a PDF Free
This free tool increases a PDF document to any size you need — 100KB, 200KB, 2MB or a figure you type — by padding it with invisible data that leaves the document untouched. Everything runs in your browser, so nothing is uploaded.
Increase PDF file size
Runs entirely in this browser tab. Your file is never uploaded.
Drag a PDF file here, or
Nothing is uploaded when you pick a file.
How it works
- 1
Choose your PDF file
Drag a file onto the tool above or click to browse. It accepts .pdf files, and the file is read directly by your browser rather than sent anywhere.
- 2
Set your target size
Pick a preset from the dropdown or type an exact figure in KB or MB. The output will match that number byte for byte.
- 3
Choose how the size is added
The default pads the file with an inert stream object that no page references, which PDF readers pass over, so the document is untouched. Switch to "increase resolution" if you want more pixels as well as more bytes.
- 4
Download the result
Press the button and your browser saves the new file at exactly the size you asked for. Nothing was uploaded, so there is nothing stored anywhere for you to delete afterwards.
Why a form would reject a file for being too small
The form is not judging your document — it is judging its byte count. That rule was written to stop people uploading unreadable 5KB scans, and it has no way of telling those apart from a clean scan that simply compressed well.
Rescanning at a higher DPI would also clear the threshold, and if your scan really is hard to read that is the better fix. If it is fine and only the number is wrong, padding it is the honest shortcut: the bytes go into an inert stream object that no page references, which PDF readers pass over, and the person who opens the file sees exactly what you scanned.
What controls a PDF’s size
Almost all of a PDF’s weight comes from embedded images and fonts. A PDF exported straight from a word processor holds real text and a subsetted font, and can be a couple of hundred kilobytes for dozens of pages. The same document scanned as images can be several megabytes for one page.
That is why PDF minimums catch people out: a properly produced, text-based PDF is small precisely because it was made well. Padding adds an inert stream object, referenced from the document catalog under a private key, which readers pass over without rendering anything.
Frequently asked questions
Will this reduce my PDF’s quality?
No. The padding goes into an inert stream object that no page references, which PDF readers pass over, so the page content is never decoded or re-compressed. What comes out is the same document, just larger on disk.
Is my file uploaded to a server?
No, and you do not have to take that on trust. Load this page, disconnect from the internet, and use the tool — it still works, which it could not do if your file had to reach a server. Nothing is transmitted, so there is nothing stored and nothing to delete afterwards.
What file formats are supported?
This page is set up for PDF documents. The tool also handles JPG and PNG images — drop any supported file in and it will detect the type from the file itself rather than the extension.
Why would I need to increase file size instead of decrease it?
Because some upload forms enforce a minimum as well as a maximum. The minimum is meant to reject scans too low-quality to read, but it catches efficiently compressed files too. When your file is legible and simply small, making it bigger is the only thing standing between you and a successful submission.
Is this free to use?
Yes — free, with no account, no watermark, no email address and no limit on how many files you run through it. Because the work happens on your own device rather than on a server, there are no processing costs to pass on.