that when you re-size to less pixels, the file size will be smaller!
This gets really complex! So far, though, the image resizer you found has worked well, and I'm grateful for it; it bugs me that the iPhoto on these Macs does not have that feature.
There are ways to be sure but each program is different. With photobucket, I couldn't find any control over it.
That image resizer (that someone else found and told me about) does seem to indicate final KB size before you save. I thought it was kind of clunky to use but it's free.
Photoshop has a Save for Web feature lets you see the KB size before you save and gives you options for lowering it.
But it is not to be assumed that making it smaller in pixel size will make it smaller in KB. If the program you're using to resize doesn't tell you the final KB in the process of saving, you'd just have to look at the newly saved photo and check its properties.
Since I use Photoshop, I don't have a lot of experience with other programs. And there are so many there's no way to cover them all.
It does get a little complex if you don't have options that make it easy for you. One option is to host on a site and link. Then you don't have to worry. But that's no fun!
I have Kodak Easy Share. It's not really difficult but I have noticed that if I "save" an image at 50% (or however that is worded) it does not mean that the kbs are going to be "half" of the original size. Sometimes I end up resizing more than once. And I do have to manually check the properties each time. No doubt I have posted a pic here that comes in a bit over the 50kb limit. [unsure]
I had a trial version of MS Office Picture Manager that had the 'resize' function and seemed to be more accesible but the Kodak software has more fun feature for 'altering' photos.
We use Preview to zoom out (reducing pixel x pixel size) and a Freeware application from the Apple site called SnapNDrag http://www.apple.com/downloads/macosx/system_disk_utilities/snapndrag.html to take a snap shot of the reduced image. With SnapNDrag you can view and change the KB size before you save the image but it is a little clunky having to take a new snap shot. The thing we like about it is you can do screen captures from almost any source.
There is also a Shareware application from Apple called EasyCrop http://www.apple.com/downloads/macosx/imaging_3d/easycrop.html that lets you drag a photo into it and resize pixel x pixel and KB size but I'm not vary familiar with it. When we looked into it you could try it out free with a watermark on the cropped image. I'm not sure what the fee is to purchase it.
You may already know about these and I'm sure there are others but, for now this works for us.