Monospace considered harmful

Posted by Michał ‘mina86’ Nazarewicz on 19th of March 2023

No, I haven’t gone completely mad yet and still, I write this as an appeal to stop using monospaced fonts for code (conditions may apply). While fixed-width fonts have undeniable benefits when authoring software, their use is excessive and even detrimental in certain contexts. Specifically, when displaying inline code within a paragraph of text, proportional fonts are a better choice.

The downsides

4′30″5′5′30″TahomaTimes New RomanVerdanaArialComic SansGeorgiaCourier New
Fig. 1. Comparison of time needed to read text set with different fonts. Reading fixed-width Courier New is 13% slower than reading Tahoma.

Fixed-width fonts for inline code have a handful of downsides. Firstly, text set in such font takes up more space and, depending on the font pairing, individual letters may appear larger. This creates unbalanced look and opportunities for awkward line wrapping.

Moreover, a fixed-width typeface has been shown to be slower to read. Even disregarding the speed differences, switching between two drastically different types of font isn’t comfortable.

To make matters worse, many websites apply too many styles to inline code fragments. For example GitHub and GitLab (i) change the font, (ii) decrease its size, (iii) add background and (iv) add padding. This overemphasis detracts from the content rather than enhancing it.

A better way

A better approach is using serif (sans-serif) font for the main text and a sans-serif (serif) font for inline code. Or if serif’s aren’t one’s cup of tea, even within the same font group a pairing allowing for clear differentiation between the main text and the code is possible. For example a humanist font paired with a complementary geometric font.

Another option is to format code with a different colour. To avoid using it as the only mean of conveying information, a subtle colour change may be used in conjunction with font change. This is the approach I’ve taken on this blog.

It’s also worth considering whether inline code even needs any kind of style change. For example, the sentence ‘Execution of a C program starts from the main function’ is perfectly understandable whether or not ‘main’ is styled differently.


What about code blocks? Using proportional typefaces for them can be done with some care. Indentation isn’t a major problem but some alignment may need adjustments. Depending on the type of code listings, it may be an option. Having said that, I don’t claim this as the only correct option for web publishing.

As an aside, what’s the deal with parenthesise after a function name? To demonstrate, lets reuse an earlier example: ‘Execution of a C program starts from the main() function’. The brackets aren’t part of the function name and unless they are used to disambiguate between multiple overloaded functions, there’s no need for them.

To conclude, while fixed-width fonts have their place when writing code, their use in displaying inline code is often unnecessary. Using a complementary pairing of proportional typefaces is a better options that can enhance readability. Changing background of inline code is virtually never a good idea.

Using serif faces on websites used to carry risk of aliasing reducing legibility. Thankfully, the rise of high DPI displays largely alleviated those concerns.

Combining colour change and typeface change breaks principle of using small style changes. Nonetheless, I believe some leniency for websites is in order. It’s not always guaranteed that readers will see fonts author has chosen making colour change kind of a backup. Furthermore, compared to books, change in colour isn’t as focus-grabbing on the Internet.