Are Roman numerals accessible and should they be used on the web?

Lewis Wake
Friday 14 July 2023

When it comes to expressing numbers, there are various methods to choose from. While the Arabic numbering system is the most widely used in Western cultures, Roman numerals still find their place in certain contexts.

However, when it comes to web content, the accessibility and usability of Roman numerals become important factors to consider.

What are the positives and negatives of using Roman numerals on the web and what are their implications for accessibility, particularly for screen reader users.

The clarity of numerical symbols and words

For numbers within the range of one digit, using words such as “one” to “ten” is a straightforward and clear approach.

In our house style, we state:

Spell out (numbers) as words for one to ten. Use numerals for numbers 11 and above and for decimals (for example, 4.52).

If a sentence starts with a number, it should always be written out in full.

If a sentence contains a mixture of numbers above and below ten, use numerals for all.

See also thousand and million.

The use of Roman numerals

Although less common in everyday usage, Roman numerals are frequently encountered in specific circumstances, such as building facades, clock faces, and most importantly the Super Bowl and Final Fantasy video games.

While deciphering Roman numerals like “III” on a clock face (representing three o’clock) is relatively straightforward, more complex examples like “MCMXLVIII” can be incomprehensible to many individuals. Especially when some schools do not teach Roman numerals.

This highlights the inherent difficulty in understanding the symbols and their usage conventions.

Clock face of St Salvators Chapel
The Clock Dial being raised to St Salvator’s College Tower in 1999, St Andrews. Link to photograph in Collections.

Accessibility challenges for screen reader users

One of the main concerns regarding the use of Roman numerals on the web is their impact on accessibility, particularly for screen reader users.

Text to speech screen readers may struggle to differentiate between the letter “X” and the number “X,” potentially leading to confusion and misinterpretation.

For instance, a screen reader might announce “Henry V Part I” as “Henry Vee Part Eye.” Even if Roman numerals are formatted using Unicode, not all screen readers can accurately interpret them.

The World Wide Web Consortium (W3C) states:

Avoid the use of Roman Numerals and unfamiliar symbols in text where possible.

These can confuse readers and are likely to be read incorrectly by text-to-speech tools.

If these symbols are necessary then ensure they are marked up correctly, using techniques such as MathML and abbreviation expansions to provide additional support.

Roman Numerals should be presented in upper case if used in isolation as they are likely to be read as individual letters.

Best practices

Currently, there is no foolproof solution to address the accessibility challenges posed by Roman numerals on the web. The effectiveness of screen readers can vary based on individual settings and user preferences. Nevertheless, several best practices can help improve accessibility.

Limit the use of Roman numerals

Minimise the reliance on Roman numerals in web content. Reserve their use for specific cases where they hold cultural or historical significance.

Provide explanations

Whenever Roman numerals are used, ensure there is additional clarification available in numerical symbols or words. This can aid understanding for all users, including those relying on screen readers.

Testing and iteration

Test the accessibility of web content that includes Roman numerals with different screen readers and assistive technologies. Gather feedback from users with varying levels of visual impairment to refine the presentation and ensure optimal accessibility.

Ensuring accessibility for all users

While Roman numerals may add aesthetic appeal or historical context to certain web content, their usage should be approached with caution to ensure accessibility for all users on the web.

It’s essential to consider the limitations of screen readers and the potential confusion that may arise when interpreting Roman numerals.

By following best practices, such as limiting their use, providing additional explanations, and conducting thorough accessibility testing, we can strive to make web content more inclusive and accessible to everyone, regardless of their familiarity with Roman numerals.

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