Pictures downloaded from iCloud are about half the resolution of the ones on my phone.

Thank you very much for your answer. Unfortunately, I spent three hours on the phone yesterday with three different people from Apple tech support. No one was able to help me. The second person said she was a Mac user and couldn't help me and that she specialized in iPhoto and sent me to another person. That person blamed it on my browser (I've tried Chrome, Firefox, and Microsoft Edge) or on my virus protection or malware, etc. None of this seems plausible because I'm able to get the images emailed to me just fine. It's only when I try to download from iCloud that the image size is reduced automatically. He suggested I download iCloud for Windows. It is already on my PC, but when I try to download it again, I get a message that says "This Product is installed." When I click on the blue Launch button, nothing happens. He finally said he was there to help with the iPhone but not my PC, that he had other calls.

I've read the link you sent. My settings were already as suggested except I do not have Optimize Storage selected as I have plenty of storage. Less than half is being used right now.

As I've done many times, I tried everything with one image today. It is a 2.53 MB image on my phone. I've been using the Mail icon to send myself images, and as I mentioned, they come through as full resolution when I choose that. I tried the method suggested in the link: tapping edit, cancel and the box with the up arrow. I email the same image, and both ways, I got the full resolution image, 2.53 MB, 4032 x 3024. No problem.

I then went to iCloud.com and had to choose two images so that I could get a zipped folder because it wouldn't let me download just one image. I then went to my Start button, Apps, and then iCloud, and the very same thing happened. With both methods, the image downloaded as 822 KB, 2048 x 1536, quite a reduction in resolution compared to the email resolution. I did this with three browsers, and with all three, the image was 822 KB when it downloaded to my computer.

Am I the only one to have experienced this problem? And doesn't Apple want their iPhone users to have a good experience even if they have a PC? I'm very frustrated.

Thank you so much for all your help! You've solved the problem that has been frustrating me for a very long time. You did what Apple support could not do. I'm an amateur photographer who uses Photoshop and Lightroom on a regular basis, and having the highest resolution possible to work with is very important to me. I can't thank you enough! Now I can move on to try to solve the problem of why, when I'm using my iPhone 11Pro, people tell me I'm cutting in and out during a lengthy phone call while I can hear them perfectly. LOL I've not been able to get a solution from Apple support, but I'll keep working on it.

Thanks so much! Most of what you said went over my head (I'm a 74 year old grandmother who is not tech savvy), but I changed the setting from High Efficiency to Most Compatible and took another picture and downloaded it from iCloud. It came through at 2.78 MB and 4032 x 3024 pixels. At the same time, I downloaded a picture taken just before I changed to Most Compatible, and that picture came through as 813 KB and 2048 x 1536 pixels, a similar loss in pixel size as I've been getting from iCloud. So it looks like from now on, I will be able to download full resolution images from iCloud.

But am I right in understanding that all the images I took before I made the change to Most Compatible will not be able to be downloaded from iCloud as full resolution? I would have to email any images that I want to print in a larger size?

I especially didn't understand the part about downloading two different versions of jpegs and sourcing a Windows tools to open and convert HEIF files, but perhaps for my purposes, my problem has been solved now?

Thank you for this!