Change a PDF’s File Size in KB 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.
When you would need a bigger file
Minimum file size rules turn up wherever documents are submitted in bulk: exam boards, immigration services, banking KYC forms and university applications. The rule is a proxy for "is this scan detailed enough to read", and modern compression is good enough that it regularly catches files that are entirely fine.
Because padding writes into an inert stream object that no page references, which PDF readers pass over, the file that comes out is structurally valid and visually identical. The validator is satisfied and the person reading your document 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, and that is the point of doing it this way. Adding bytes to an inert stream object that no page references, which PDF readers pass over changes the file’s size without touching the part of it that describes the document, so there is no mechanism by which the quality could drop.
Is my file uploaded to a server?
No. The entire process runs in your browser using the File and Canvas APIs and pdf-lib. Your file is read from your own disk, changed in memory and handed straight back to you. You can confirm it by opening your browser’s Network tab while you use the tool — there is no upload request, because there is no upload endpoint.
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?
It is rarely a want, usually a requirement. A portal has refused the file for being below its minimum, the scan itself is fine, and rescanning it at a higher DPI means finding the document and the scanner again. Padding gets the number where it needs to be in seconds.
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.