Increase PNG File Size Online — Free and Exact
This free tool increases a PNG file to any size you choose by adding invisible metadata chunks to it. The picture itself is untouched, so it looks exactly the same. Pick your PNG, enter a target in KB or MB, and download — nothing is uploaded to a server.
Increase PNG file size
Runs entirely in this browser tab. Your file is never uploaded.
Drag a PNG file here, or
Nothing is uploaded when you pick a file.
How it works
- 1
Choose your PNG file
Drag a file onto the tool above or click to browse. It accepts .png 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 extra tEXt metadata chunks, an ancillary PNG block that decoders are required to ignore, so the image 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 extra tEXt metadata chunks, an ancillary PNG block that decoders are required to ignore, 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.
Why PNG files behave differently
PNG is lossless, so it never throws detail away, but it is built for flat colour: screenshots, logos, diagrams and line art. A signature or a simple graphic can compress to a few kilobytes because a PNG can describe long runs of identical pixels almost for free. Photographs go the other way and stay large.
Padding a PNG adds ancillary tEXt chunks before the file’s IEND marker. Ancillary chunks are the part of the specification that says decoders may ignore what they do not recognise, so the IDAT pixel data is untouched and the image is identical.
Frequently asked questions
Will this reduce my image’s quality?
No, and that is the point of doing it this way. Adding bytes to extra tEXt metadata chunks, an ancillary PNG block that decoders are required to ignore changes the file’s size without touching the part of it that describes the picture, 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. 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 PNG images. The tool also handles PDFs and the other image format — 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.