Image Quality vs File Size for 4k Images vs 1080 Images for Website Upload

[MISSIONARY ENTERPRISES]

Hi, thank you for taking the time to read! 

I'm currently making many images for a photo gallery on my website, and i want to make sure that the website doesn't slow down because of the image sizes being too large, but at the same time I don't want to cut down on the image quality too much either.  Ive done some research on the different image sizes and appropriate size for them as well. 

I have 2 template sizes for 4k Images and 1920x1080  Images.

Would it be better to make an image at 3840 X 2160 (4k) and recude the image quality to low or medium

or to create the image at 1920 x 1080 and keep the image at high /very high quality?

I am also looking for future proofing the images for projector use as well, meaning they would be shown at a alot more larger scale on a project screen. (but that's just a side question) The main concern is for uploading to a website for best quality and file size. 

Thank you so much for the taking time to answer these questions! 

[didiermazier]

I would say both : 1920 and quality 75 would be sufficient if it is just for browsing… And the projectors in the better case are 1920 also… but it also depends of what is on the image…

That being said, some CMs are managing these problems with automatically setting images at various sizes according to breaking points of the viewports. In this case the loaded image is not the same for a mobile phone than for a computer or a smart TV…

Joomla or wordpress do that very well with free extensions…

[MISSIONARY ENTERPRISES]

Thank you for your reply sir! 

[Test Screen Name]

There's not really such a thing as future proofing, but for maximum future life, make sure you save Both the original PSD files, and a public format at highest quality, in addition to the deliverables you need today.