Why does the file size increase?

After looking at the beautiful siggies I thought I would try my hand at it. I looked at the sizes, 550 x 134 pixels at 72 pixels/inch, I fiddled with the background until the file size on my computer was only 28 kB, I upload it to photbucket, where it shows up as being 24 kB, but when I try to upload it to thecatsite, it ends up 34 kB? I don't want to just resize it, I would like to understand why it is being a byte pig. I see other siggies with the same dimensions and they have much fewer bytes.

That has happened to me a couple of mine as well

Did you use the "save for web" option in photoshop? You can adjust the size with that.

I also noticed with photobucket that if you do change the file size you have to rename the file before you upload it again or it still shows up as the larger size.

Stormy, that did the trick! I did not even know there WAS a save for web feature. All the photshop stuff I do is for reports, except for the playing around I do with websites.

Hot diggety, the 1st pic is the one I had posted as an attachment, the second one is my new siggy. I even got some more detail into the one that only has 15 kB.