What's supposed to happen? I've converted the file. I get the success green check in the Jobs box. Then what? Where is the mobil file? I clicked on the finished job and at the bottom of the screen it says the mobi was saved in some temp directory, but when I look, it's not there.

[Aximtreo]

I never had any success with caliber for converting files. I googled and found a file called epub to mobi and it works like a charm. Hope this helps.

[Mr FuFu]

By default they are saved in Documents > Calibre Library

Have you tried selecting the book and press button "open containing folder" to see if it's there?
Or try right-clicking the book and choose "view" and then "view specific format):

Then a window opens where you can see - and choose the different kinds of formats:

You can also check it by opening "Edit metadata": at the right you can see all the different formats of the book:
.
I know that under "show job details" it says that it has been saved in a temp folder, but I think that is just a "temporary" folder it uses during the converting (I don't really know about that part...) but my "converted" files are stored in the original containing folder.
Hope you can make it work. I never have any problems and it is easier to convert the files where you store them and can check them right away.

By default they are saved in Documents > Calibre Library

This was the one thanks!

Hi, I tink that your problem comes from the fact that your are not used with Calibre books management, windows, and functions. Me not english native writer, and my Calibre is in french. But I think it is done the same in any lenguage, hope the follwing explainations are ok.
Simply keep your Calibre open, the new file is simply added next to the other file, in your Calibre library and interface.
Just look at your Calibre, with all your books likst, select your book, the one you converted, click on information, and tadaaaaam, your see it on the right up side on the window...
If you select the title of your book in Calibre window, and make right click, you will even find the exact locations of your book... in both epub and mobi, select just "open directory" (my personal translation for how it works for me in french).
Usually, Calibre books are in Calibre library in your Documents file (but if you selected other place when you installed Calibre, it could be different).

Hope this help, if needed I can make some screen prints

What's supposed to happen? I've converted the file. I get the success green check in the Jobs box. Then what? Where is the mobil file? I clicked on the finished job and at the bottom of the screen it says the mobi was saved in some temp directory, but when I look, it's not there.

If you want to transfer the e-books to other devices or convert e-books to other type, please use the best e-book manager&converter--- Calibre. Calibre is a freeware which can convert e-books from format to format. Calibre supports the input formats: CBZ, CBR, CBC, CHM, EPUB, FB2, HTML, LIT, LRF, MOBI, ODT, PDF, PRC, PDB, PML, RB, RTF, SNB, TCR, TXT. The output formats: EPUB, FB2, OEB, LIT, LRF, MOBI, PDB, PML, RB, PDF, SNB, TCR, TXT.
If you want to know how to convert from epub to mobi via calibre, please refer to this link:http://www.epubor.com/how-to-convert-ebooks-with-calibre.html.
Hopefully it can help you and god bless you!

If you need to convert formats in the future, try using online service https://convertio.co/epub-mobi/. It's free and easy to use.

When I click on send to a kindle it offers to turn it into a mobi for me and it seems to work. And then on the right hand side are little links to the epub and the new mobi verson if I wish to open them.