Min Requirements for eCommerce Images

[ChrisNewtowner]

Hi all!
I need to upload some images to an ecommerce platform, and they require JPG/JPEG images, minimum 5 mb, max 20 mb in size and 1800x2600px as best practice.
I do have big raw images, some of them 20+ mb each, but everytime I want to save them, the jpg compression produces small size files, between 1 and 3 mb. I need them to be at least 5mb.
I've tried the save as, save a copy, export as, export for web options without sucess.

Is there any way I can produce jpg files of at least 5mb?

Thank you!!!

[Stephen_A_Marsh]

The requirement for specific pixel dimensions overrides the final file size which is dependent on image content. If at maximum quality then this is just how it is. It's nonsense for them to demand a minimum 5mb when given pixel dimensions are being followed.

[ChrisNewtowner]

Thank you for your help Stephen!
That's their "best practice" px dimension requirement, but it doesn't need to be exactly that width/height. 
What size (w x h) do you think is ok to meet that 5mb min requirement? I've tried upcaling  2x and 3x, but still hard to reach that 5mb line, as there's a lot of white on some images. 

Thank you again for your time!

[Stephen_A_Marsh]

It's not about file size, the smaller the better if the quality is good. Does the image look good at display size? Does the ecommerce platform use a pan/zoom feature?

[ChrisNewtowner]

Yes, this is a german ecommerce site called Zalando, and the platform uses the zoom feature for images. I don't understand why they need such a big images but they won't accept the files if they don't meet the 5mb min requirement :/.

 

[Stephen_A_Marsh]

Talk to them! Otherwise, if sanity doesn't prevail, use a larger pixel size and the highest quality level (least compression) to meet the imposed minimum requirements.