Converted books are using their own font size

[billmandy]

Converted books are using their own font size. Why is this happening?
The font tends to be small, and I have to set the size of the font on my Paperwhite to 90% or so in order to be able to read it.

I am converting from EPUB to AZW3. What am I doing wrong?

[retiredbiker]

What you get in the output font size will depend on both whatever is in the source epub, and what settings there are to tell the conversion what to do with it.

To find out what is in the epub, you can open it with the Editor and look at the css to see what font sizing is in use, but if you don't know how html and css works, this may just confuse you. It is not necessary, but just might be helpful.

No matter what is in the source book, you can change the output font sizing with some conversion settings.

Look at the top three items, pictured below, in the Fonts tab of the Look and Feel section in the conversion options, when converting a book. Hover for tool tips, then play with the settings to get the output font size you want. (In the image here it is all turned off, because most of my conversion is from OCR text and I edit the result and change the css anyway.)

(Note that once you have converted a book, the settings are saved for that book. For a more global place to do the settings, look in Preferences / Conversion / Common options. A setting put there will apply to a new book you haven't converted before. So once you have converted a book, changing global settings will not affect it anymore, you have to change the book-level settings. This confuses a lot of people at first.)

[theducks]

I gave up using rescaling (as it appears @retiredbiker has done)

I find it easier-faster to adjust the CSS using the editor.

Ctrl right-click on the class="XYZ" and the editor will jump to the CSS definition

For more nested CSS, View:Inspector may be a help (and No!, I can't train on its proper use. I just muddle thru )

[billmandy]

Well, the "Disable font size rescaling" is off in the global settings.
But I still see books with small fonts from time to time.

But I guess there is no checkbox in Calibre that could solve this.

[Quoth]

I bought one book off Amazon were the CSS for all text except headings was
font-size: small;
Which is stupid.

I searched & replaced to font-size: 1.0em;

[Sirtel]

Originally Posted by Quoth

I bought one book off Amazon were the CSS for all text except headings was
font-size: small;
Which is stupid.

I searched & replaced to font-size: 1.0em;

This is common, unfortunately. I've seen it in hundreds of books. I just mass delete it, the result is the same as in replacing with 1em.

[Sirtel]

Originally Posted by billmandy

Well, the "Disable font size rescaling" is off in the global settings.
But I still see books with small fonts from time to time.

But I guess there is no checkbox in Calibre that could solve this.

The only way is to edit the css, as already said.

[slm]

Originally Posted by Sirtel

The only way is to edit the css, as already said.

If you don't mind doing violence to the author/publisher's choice of relative sizes, you can just add CSS in all conversions (in Look and Feel, Styling, Extra CSS):

* {font-size:1em !important}
or--slightly safer--
p {font-size:1em !important}

I don't use this, but for many years I used the the equivalent to make all text bold because Amazon's fonts in those days were all too light for me to use comfortably.

Once in a while, of course, it did really mess up the book.

[Quoth]

Originally Posted by Sirtel

This is common, unfortunately. I've seen it in hundreds of books. I just mass delete it, the result is the same as in replacing with 1em.

Yes, I know it's the default. Years of Electronics and Programming put me in the habit of mostly entering stuff even if default.