Tutorial: Reducing line spacing in Kindle readers

[jackm8]

Default 'Spacing' settings are too wide for many people on its narrowest setting. Here's what I use to fix this. This process is not modifying line spacing, it's achieving the look of smaller line spacing by increasing scale of fonts files. All that's needed is uploading a modified custom font file to the device, selecting it, and it should work on all reflowable books that Amazon supports. This solution works on every book in every format that supports custom fonts. It works on store bought books, and it works on sideloaded books.

It should also work on every reader that supports custom fonts, but it's really not needed on others, because they tend to support custom reading apps that allow smaller line spacing settings, or their default readers support such settings. It's also possible to modify line spacing directly on epub books, because style commands of the "line-height:" family work on them. Kindle simply ignores this setting once epub is converted to one of it's formats. I think that 'line-height' command works on azw3 format, but then you're missing out on a few goodies that kfx format supports, like native cover thumbnails, and it's only viable for sideloaded books.




Requirements:

Spoiler:

- Windows, Linux or Mac and some knowledge on how to work with files.
- FontForge program: https://fontforge.org/en-US/ (freeware)
- Custom font files: Use your favourite fonts. It's also possible to use default Amazon fonts, by downloading them from their site, modifying them and adding them into custom fonts folder.
- Any Kindle that supports custom fonts.

Instructions:

Spoiler:

- Open FontForge:
- File -> Open (Ctrl+O) — Open your font file
- Encoding -> Compact — This will hide empty glyphs, and speed up the process.
- Select all glyphs: Edit -> Select -> Select All (Ctrl+A) — Glyphs must be selected for adjustments to be made.
- Window -> New Metrics Window (Ctrl+K). — I use this to preview changed. Input some text into the smaller top window, and it'll show a preview. Top and bottom of fonts can overlap in preview, we want this. They should not overlap each other in width, though.
- While all Glyphs are selected: Element -> Transform:
— Origin: Glyph Origin (make sure that this dialogue is set to 'Glyph Origin')
— Scale Uniformly (100% means no change, 130% scales font by 30%. I tend to get best results at 120% scaling. With values of around 110-150% also being usable. Higher values mean smaller space between lines. At 200%, lines will certainly overlap on every font.
— transfer all layers (off)
— transform guide layers too (off)
— transform width too (on)
— transform kerning classes too (on)
— transform simple positioning ...... (on)
— round to int (off)
- Even though 'transfer width' automatically changes width of glyphs, it's occasionally still needs to be adjusted a little. Larger scale requires larger width changes. Check 'New Metrics Window' input a few all caps sentences, and a few words to see changes that were made then proceed to the next step if there are problems.
- If fonts overlap, increase width of glyphs: Metrics -> Set Width (Ctrl+Shift+L) — Do this in main FontForge window, not in New Metrics Window. Select "Increment Width by:" 20 to 50 for 130% scale is usually enough. IMPORTANT: This process can be very CPU intensive for font files with many glyphs, and can take minutes on a desktop. Just leave it open until it finishes, then you should see the changes immediately in the 'Metrics Window'. Fine tune fonts with further instances of "Set Width" if needed. Dialogue accepts minus values as well. Metrics -> Auto Width can be used to achieve similar results, I just haven't tested it thoroughly.
- After all gyphs are processed: Element -> Font info (Ctrl+Shift+F). This step names fonts. It's optional, but a good practice in organising fonts. Only change "PS Names" entries. I like to keep modified and original font on my device. I just add scale by which I increased fonts at the end of each "Footname", "Family Name", and "Name for Humans". "Fontname" doesn't accept spaces. After changes are made, you may be asked to auto change XUID, you may retain or auto generate this, it should have no effect on Kindle readers.
- Export font as a new file: File -> Generate Fonts (Ctrl+Shift+G).
— Select 'OpenType (CFF)'
— Name new font. —
— It's not unusual to get errors, just click 'Generate'
— New font will be created in the same directory as the source font.
- Repeat process for Italic and Bold fonts of same font family if needed. Italics tend to be used in books, while bolds are very rare. In case that there is no Italic font family, or there is one but is named incorrectly, Kindle will automatically slant normal fonts. For Serif fonts, this isn't ideal, but San-Serif fonts usually don't look that different, so they're often omitted. Some care needs to be taken when naming Italic and Bold fonts so they all fall under the same font family. Under 'Font info' dialogue, 'Family Name' must be the same. And when fonts are generated, it's best to have Italic and Bold font named exactly the same just with -Italic at the end of the file. -It, -Bold, -BoldIt can also be used. Just use some common sense here, and name fonts in the same way as your source fonts are.
- Copy new fonts to Kindle into Fonts directory, and test them out on a few books. Look at italic passages, how fonts fare with all caps titles, and in different layout settings.

If all goes well, you're now in possession of a Kinde reader that is capable of displaying sensible line spacing.

Drawbacks and notes:

Spoiler:

- With introduction of WinterBreak and ability of installing Koreader on all current kindles, usability of this process is reduced to people that don't want to jailbreak their kindle. Koreader has various font settings that are more practical than modfying fonts.
- This process needs to be done for every font that you use, and for all font family in use. For serif fonts this means at least a regular version and italic version.
- Scaling is automatic, it may cause fonts to look slightly different at times.
- Because font scale is increased, this effects font size setting on the device. Smallest font size settings will be larger, largest will be even larger. The amount of Scaling that is input in FontForge effects this a lot. Going with Scale of 200%, for example, will give some silly results. Though it's possible to get something usable out of them by selecting wider line spacing settings in the device.
- Font names of adjusted fonts in font select window on devices are oversized.
- Spacing between paragraphs is also reduced.
- Wordwise works, but spacing remains the same. Fonts for definitions appear smaller.
- Process isn't perfect. Many fonts have finely tuned glyph widths. Scaling and expanding width of glyphs affects the look of fonts.

Threads that talk about this issue and some links:

Spoiler:

https://www.mobileread.com/forums/sh...d.php?t=286385
https://www.mobileread.com/forums/sh...d.php?t=355703
https://www.mobileread.com/forums/sh...d.php?t=184056

Amazon font set: https://developer.amazon.com/en-US/a...nes/typography
FontForge Documentations: https://fontforge.org/docs/index.html

Fonts:

Roman Antique:
https://online-fonts.com/fonts/roman-antique
Charis:
https://software.sil.org/charis/
https://software.sil.org/fonts/
Chareink:
https://online-fonts.com/fonts/chareink
https://software.sil.org/fonts/
https://www.mobileread.com/forums/sh...=184056&page=3
Cormorant:
https://fonts.google.com/specimen/Cormorant
https://github.com/CatharsisFonts/Cormorant
Inter:
https://fonts.google.com/specimen/Inter
https://github.com/rsms/inter
Cardo:
https://fonts.google.com/specimen/Cardo
https://fonts.adobe.com/designers/david-j-perry
Questrial:
https://fonts.google.com/specimen/Questrial
https://github.com/googlefonts/questrial
EB Garamond:
https://fonts.google.com/specimen/EB+Garamond
http://www.georgduffner.at/ebgaramond/index.html

Some Before/After screenshots from my Kindle. Because fonts are scaled, font size settings differ. I tried to match some samples, but it was never possible to get them exactly the same. It should give and idea what to expect. There's also a font zip file in attachments with eight fonts, that I've scaled by value of 120 to 130%. All fonts scaled are freeware, or open source. Links to original fonts are provided in the links section.

That's it. I hope someone finds it useful. I may add a few more screenshots and fix some typos, in the meantime, have a Happy Christmas everyone.


POST HISTORY:
1.0 Initial post
1.1 Included Linux as optional requirement
1.2 More fonts, more samples. Clarified width step. I previously stated that all fonts need to have width corrected. It turns out that this is incorrect, as most don't require this step.

[BionicGecko]

Thanks for this, it’s one of the things that really do bug me on the Kindle. Will give it a shot!

[JSWolf]

This does not work for KFX as KFX uses a forced fixed kine height.

[nabsltd]

Originally Posted by JSWolf

This does not work for KFX as KFX uses a forced fixed kine height.

Because the font resizing technique listed here increases the size of the font while maintaining the original line height metrics, this should work on any renderer that respects the font metrics, which the KFX renderer appears to do.

[JSWolf]

Originally Posted by nabsltd

Because the font resizing technique listed here increases the size of the font while maintaining the original line height metrics, this should work on any renderer that respects the font metrics, which the KFX renderer appears to do.

Trust me. It won't work. Just look at ChareInk6/ChareInk6SP. They reduce the line height for KF8 but do not reduce the line height for KFX. Also, the size of the font is not increased. I did happen to find this out by accident. But the same font files work on Kindles, Kobos, and other Readers with no problem.

The idea is to reduce the line height without increasing the font size. You can do this with KF8 but not KFX.

[jackm8]

Trust me, it works. All sample images are taken on KFX files. Fonts work on other formats as well, but I specifically did all my testing on KFX, because that's the format that I use.

[JSWolf]

Originally Posted by jackm8

Trust me, it works. All sample images are taken on KFX files. Fonts work on other formats as well, but I specifically did all my testing on KFX, because that's the format that I use.

But it's not correct. You are not supposed to make the font size larger. You are supposed to keep the font size as is and make the line height smaller.

[Quoth]

Originally Posted by JSWolf

But it's not correct. You are not supposed to make the font size larger. You are supposed to keep the font size as is and make the line height smaller.

Only possible by switching to a not-Kindle.

This works because it creates messed up font-metrics. The font is bigger than it should be and the line-spacing (if not set in CSS) is based on the font at correct size. So when user changes the GUI font size back to normal the line spacing reduces.

I had thought this was a way to over-ride Amazon stupidity (you also need a negative 1.5% approx overall margins).

In the end, it's less work to buy a Kobo and use the Paperwhite Serial number (pre-2024 models) for Download and Transfer, using a plug-in on Calibre to automatically remove DRM. Then convert to epub and read on anything not a Kindle to avoid Amazon's artificial stupidity.

This is a good idea, but it's too much work for most people.

[JSWolf]

Originally Posted by Quoth

Only possible by switching to a not-Kindle.

This works because it creates messed up font-metrics. The font is bigger than it should be and the line-spacing (if not set in CSS) is based on the font at correct size. So when user changes the GUI font size back to normal the line spacing reduces.

I had thought this was a way to over-ride Amazon stupidity (you also need a negative 1.5% approx overall margins).

In the end, it's less work to buy a Kobo and use the Paperwhite Serial number (pre-2024 models) for Download and Transfer, using a plug-in on Calibre to automatically remove DRM. Then convert to epub and read on anything not a Kindle to avoid Amazon's artificial stupidity.

This is a good idea, but it's too much work for most people.

You can change a font's metrics to reduce the line height without increasing the font size. It works in KF8 but not KFX. I've done it with ChareInk (now ChareInk6/ChareInk6SP). The size of the characters is the same size as it should be. And because the Kindle uses a different metric for line height then other software, there is no problem using the font outside of a Kindle. But if you use ChareInk6/ChareInk6SP with KFX, the line height will not be reduced as KFX forces the line height.

As for the sample in the first post, it's ugly because you are taking a really ugly font and making it larger then it should be. So you get more of a very ugly font.

[jackm8]

Originally Posted by JSWolf

As for the sample in the first post, it's ugly because you are taking a really ugly font and making it larger then it should be. So you get more of a very ugly font.

No, idea what made you so angry, but attacking fonts is just silly. You're also wrong that they're larger. All glyphs are the same height, same width, they are identical in the first sample! Spacing is a tinny bit larger on modified sample, and lines are, off course, much narrower. It's probably that narrower lines gave you the impression that glyphs are larger, when in fact they are the same.

Originally Posted by Quoth

This is a good idea, but it's too much work for most people.

It looks like a long process, but it shouldn't take more than ten minutes per font file, after one is familiarised with programs. I just tried to cover everything, as things can go wrong in FontForge.

It's less work in the long run, though. Once fonts are fixed, they work on every book on the device. Another plus is that it works on store bought books, no need to dedrm them.

[j.p.s]

Is there some specific reason linux doesn't meet the requirements?

[Flaviocc]

@jackm8

Do you have ahy ideia where in font forge I can setup more weight to a font tha I use ?

That font I need to load on Ipad to use. The original is thin so I need more weight.

Tks if you can hlep me.

[jackm8]

Originally Posted by j.p.s

Is there some specific reason linux doesn't meet the requirements?

It should work. I meant pc as personal computer so linux/windows. Basically the only requirement is a system that can run FontForge, so you could theoretically run it on android.

Originally Posted by Flaviocc

@jackm8

Do you have ahy ideia where in font forge I can setup more weight to a font tha I use ?

With all glyphs selected:
Element -> Style -> Change Weight (Ctrl+Shift+!).

[Flaviocc]

Tks 👍🏽

[jackm8]

I update the samples in the first post, and added a few extra scaled fonts. With WinterBreak now available, this process is now outdated for everyone with it. It should still be viable for people not willing to jailbreak their Kindles.

Regarding fonts, I'm only posting open source or freeware fonts, so no Adobe fonts. Also no Amazon fonts, as I've no idea regarding their licencing model. My own taste prevailed regarding fonts that I included. Coromrant and Cardo are both Garamond inspired fonts. EB Garamond is one of the first open source Garamond fonts. Charis and it's derivative Chareink appear to be popular here. I included both. Questrial is Futura like open source font, while Inter is a popular sans serif font. I'm also a longtime FC Internazionale fan, so that's an extra reason for including it.

Samples are all taken with 'Bold' setting in the reader set to lowest possible. 'Spacing' setting is in every case set to the smallest possible.