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Is there any (free?) software that will help me to convert existing JPG files into a specific file size on disk?

(I assume that the software will estimate accurately compressed file size during the save.)

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A "certain size" as in pixel dimensions or as in file size? – Mokubai Jan 13 '11 at 9:22
I'd say file size, @Mokubai, given the reference to compression. – Arjan Jan 13 '11 at 10:31
do you want to create dummy files, or convert existing files into files of a specific disk size? – Arjan Jan 13 '11 at 10:33
convert existing. file size on disk – Pablo Jan 13 '11 at 10:52
(Next time please note the "edit" link. Thanks and success!) – Arjan Jan 13 '11 at 12:19
up vote 5 down vote accepted

Irfanview is pretty good and does it for jpeg- just install it WITH the plugins and setting file size should be a save option. I quite like Irfanview in fact, it's light, easy, quick and does batch operations nicely :)

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The command line ImageMagick supports a maximum file size:

-define jpeg:extent=400kb
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Paint.NET gives the file size when saving:

Show file size on saving

Simply change the quality setting to get the size you want.

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For quick and easy image resize I always use and recommend Picture-Resize. It's very easy to use and blazing fast.

It does not have a GUI, you just change the filename in order to change the parameters of the image resize operation. A very unusual but cool way to operate.

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The question seems to be asking about file-size not image dimensions – RedGrittyBrick Jan 13 '11 at 10:28
yep, it's about file size, not dimensions – Pablo Jan 13 '11 at 10:54
you can do a file size resize with the program I mentioned – Patareco Jan 17 '11 at 3:53
Upvote because this program is one of the most versatile applications to perform batch image resize. For some operations irfanview is quite overkill. This program is specially good for sending it to family; for example the program application PhotoResizeK1000NMROEH.exe will resize images to 1000KB preserving everything. The user will only have to place it in the desktop and drag/drop the pictures or folders to convert. It does not get easier than that (in the webpage the program settings can be configured) – obaqueiro Oct 8 '11 at 11:19

Irfanview with the Save-for-Web plugin does this.

  1. Install irfanview.
  2. Install and download the plugin. The recommended way to do this is to just download and install the "All plugins" package from their website.

In irfanView, the plugin is accessible via "File", "Save for web (plugin)". There's a "Compress for size" option that lets you enter a desired file size and then makes an approximation of what you entered.

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