Those of us dealing with large numbers of images stored on a network server (and not having the budget of organisations like Google etc) have to live with finite resources and can't store full size digital images as they are delivered from the camera. Apart from the cost, if you place a bunch of such images on a web page, even with broadband, the page loading time will grow to the point that will mean no-one will wait for them all to appear.

This means you have to re-size them. Changing the dimensions has always been easy, and you can set height and width in seconds.

The file size has however been a different story, and if you wanted to have a maximum file size for a picture of say, 100 kB, then you just had to try repeated compression levels until you got near to the desired value. Since the amount of compression needed varies with the image content, there's no rule like "Reduce a 4 MB pic by 55% to get about 100k" and the actual compression needed can range anywhere from 80% to 30% to achieve the same result.

Without any more ado, the faithful that have stuck with Irfanview to manipulate their image files, and supported the program now have a new toy in the most recent release, with the option to tell file saves what file size is wanted. So simple, yet so long in coming in a piece of free code.

Irfanview web site

You're looking for Version 4.20 or later, and you must download and install BOTH the program and the plug-ins, then go and have an extra tea or coffee from all the time saved

Good grief.  If you are shrinking them all to that extent it is a major undertaking.