How can I INCREASE jpeg file size for an image with a white background?

You could try adding noise (or grain) to the white background. This would make the JPEG compression less efficient and would result in a larger file size.

It's a dumb workaround for a silly requirement, but if you need a bigger filesize, that could help!

For JPEG files the quality level makes the most difference, but of course you said it’s already set to 100%.

After that, file complexity is a big factor. The more detail and noise, the larger the file. A photo with a large flat white background typically compresses very easily because it’s so simple, so it is hard to make that type of file larger.

taridonohue wrote:

What he's asking is how to increase the file size of a photo - not blow it up to make it bigger. Some stock photo agencies require a file size of at least 5Mb, and I am facing this puzzle myself.

To get a file larger than 3 to 5MB, it would help a lot if the file format could be TIFF or PSD instead of JPEG,  if the bit depth can be higher than 8 bits per channel, things like that. Can you post a URL of a stock submission web page where the file requirements are listed, or at least paste the complete submission requirements? It would help us see if there are aspects of the requirement that could be changed to achieve a higher file size.

If nothing else, the number of pixels could be artificially increased (by scaling up with Resample enabled).

Also, for clarity:

MB = megabyte, which is probably what they want.

Mb = megabit, which is only 1/8 of a megabyte so it is important to be use the right abbreviation.

Finally, I have to agree: A file size requirement is kind of ridiculous because it doesn’t indicate anything about image quality on its own. To have any meaning at all, a file size requirement needs the context of which file format, which color mode (file size is different for RGB vs CMYK), what bit depth, what compression level, what pixel dimensions… Otherwise it’s too easy to take a terrible picture, futz with some technical option to artificially bloat up the file size, and send it in. We know it isn’t you that requires a certain file size, but it does need to be said that file size has no meaning on its own.

This is really a simple request. What he's asking is how to increase the file size of a photo - not blow it up to make it bigger. Some stock photo agencies require a file size of at least 5Mb, and I am facing this puzzle myself.

Agreeing with the others.

A 3MB requirement is nonsense. Expanding the photo to make it larger actually will decrease the quality.

I don't understand why you will blow up the file size of your jpegs. What do you want to achieve with this?

If you exported your RAW with the 100% setting and without a file size limit you get the best qualitiy you can get. There's no chance to get more.