Clear and concise communication is a prized skill. Whether you’re crafting a business proposal, drafting a legal document, or creating marketing materials, the ability to convey complex ideas in a simple and easily understandable manner is essential.

Readability metrics are a critical piece of the communication puzzle. In this post we’ll delve into the world of readability metrics, exploring why they matter, how to use them, and potential drawbacks.


What is readability and why does it matter?

Readability refers to the ease with which a piece of writing can be understood by its intended audience. It involves assessing factors like sentence structure, word choice, and overall complexity to ensure that the content is clear, accessible, and effectively conveys its message. This is distinct from legibility (also key in marketing communications) which concerns how well the visual characteristics of the text can be recognized by the reader.

Here are three reasons why readability matters for marketers:

1. More effective marketing messaging

Readability isn’t just a matter of aesthetics; it has practical implications for your business. Complex and convoluted writing can lead to confusion among your target audience, diluting your brand voice and resulting in lost opportunities and decreased engagement.

Clear communication, on the other hand, can enhance your marketing effectiveness in a world where everyone is vying for ever-decreasing consumer attention spans.  A study on branded Facebook posts found a strong correlation between a good readability score and increased engagement and awareness[1], which helps to drive brand loyalty and purchase intent[2].

2. Meet increasingly stringent regulatory requirements

Many jurisdictions recognize the importance of readability, especially for consumer-facing documents. Some regulations may expressly mandate a grade level requirement (such as for United States health insurers)[3]. Others contain more generic readability obligations that require companies to ensure their advertising material is readable to the relevant audience.
For example, the United Kingdom’s Financial Conduct Authority (FCA) has provided the following guidance relating to the new Consumer Duty[4]:

  • When communicating about the product, firms should consider the characteristics of the consumers within its target market and tailor communications to meet their information needs.
  • For mass marketing products, firms should take into account research relating to poor or low levels of numeracy and literacy and communicate information in as simple a way as possible to support understanding for these customers.
  • Firms should take particular care when communicating with consumers in vulnerable circumstances, taking account of their needs.

These types of regulations are more difficult to comply with than “strict threshold” regulations as they are more context sensitive. Accordingly, you should create clear internal guidelines for how your company complies with these standards, create processes to enforce them, and audit against them regularly.

3. Tailor communications for vulnerable audiences

Difficulty reading complex texts is a global phenomenon. The average American reads at an eighth-grade level, and close to one-fifth of American adults cannot understand a fourth-grade text[5]. In Australia, 13% of adults read below a Year 7 level[6], and in the UK 15% of adults read below the standard of an 11-year-old[7]. Best practice communication involves working within these parameters to ensure that your audience can understand the information you provide.

This is particularly important where there can be severe consequences from misunderstanding, such as in the finance and healthcare industries.


Using readability metrics

Readability metrics are algorithms that assess the complexity of a piece of writing based on factors such as sentence length and syllable count. These metrics generate a numerical score that reflects the readability level of the text. Often, these are translated into a US grade level such as “4th grade” or “10th grade”[8]. The lower the grade, the easier the text is to understand.
The most common formula is the Flesch-Kincaid readability formula – available in most modern versions of Microsoft Word – but there are many which can be used in difference circumstances. For example, in the United States, the Centers for Medicare & Medicaid Services (CMS) recommends using the Fry and SMOG readability methods for assessing the readability of health insurance communications. These require specialist software or time-consuming manual processes to compute.

Typically, most readability formulas work best on longer pieces of text and provide a score for the overall passage rather than a granular breakdown. This can be cumbersome when trying to identify which sentences should be reviewed for improvement, particularly when creating short form copy. However, tools like Red Marker can highlight key sentences within marketing content that may benefit from simplification, irrespective of their length. This makes the task of enhancing readability more manageable and effective.


Using readability metrics within your organization

Getting started with readability metrics doesn’t have to be difficult. Here’s how:

  1. Understand your audience and communication goals: For the most common types of marketing material you create, consider your audience’s age, education level and assumed prior knowledge. Work at the lowest common denominator. Add this information to each of your audience segments or create new segments if needed. Then consider what you need the audience to digest from your material: is it a simple message from some product marketing, or a detailed understanding of the implications of a health insurance policy? This will impact your approach to readability.
  2. Identify your legal obligations: Understand the regulatory requirements your marketing communications are subject to. Are they advisory, strongly recommended or mandatory? Are there different requirements for different jurisdictions or products? Create a process to comply with these obligations and ensure it is auditable. Be especially mindful of any regulations which impact how you communicate with vulnerable groups.
  3. Implement appropriate readability tools: There are several tools available to measure readability. Microsoft Word, for instance, offers a built-in Flesch-Kincaid score for entire documents. Additionally, tools like Red Marker provide reading age estimates using multiple readability metrics and highlighting sentences that may need attention.
  4. Iterate, retest, and audit: The process of enhancing readability is iterative. After making improvements to your content, retest its readability using the same metrics. Keep a record of these measurements for auditing purposes, ensuring that your communication consistently meets the desired readability standards.


Navigating Drawbacks to Readability Metrics

While readability metrics are valuable tools, they’re not the sole determinant of effective communication. They should be used in conjunction with other factors, such as context and tone, to achieve optimal clarity. Here are some common pitfalls to watch out for:

“Gaming” the score

While it’s possible to improve the readability scores by using simpler words, this approach might compromise the ultimate goal of clear communication. Sometimes, using less common words that more accurately convey your message results in better understanding. This is particularly so in the medical context, where substituting specific medical language could lead to misunderstanding.

Modifying critical legal disclosures

Balancing readability with legal obligations can be challenging. Legal disclosures are often required by regulation, and fly in the face of best communication practices by using archaic legal language and very long sentences. Unfortunately, they are a fact of life and should never be modified without consulting your legal and compliance teams – even if they  impact overall readability.

With the wording of legal disclosures often set in stone, you may wish to explore other avenues to improve comprehension such as layering[9]. Of course, you can still test and improve the readability of your primary messaging.



Readability metrics are powerful tools that help you create content that is clear, comprehensible, and effective. They offer insights into the accessibility of your writing, making it easier to enhance communication with your target audience.

While they have their limitations, when used wisely and in conjunction with other considerations, readability metrics can be a crucial asset in the professional writer’s toolkit. By embracing these metrics and striving for transparent, accessible communication, you can unlock a world of opportunities and strengthen your connection with your audience.

Red Marker is helping businesses around the world in industries such as financial services, healthcare and insurance adhere to readability guidelines and regulations, providing automated document analysis using the most common readability metrics and highlighting areas for improvement.


  1. Dimitris C Gkikas et al, How do text characteristics impact user engagement in social media posts: Modeling content readability, length, and hashtags number in Facebook, International Journal of Information Management Data Insights, Volume 2, Issue 1, 2022, 100067, ISSN 2667-0968, https://www.sciencedirect.com/science/article/pii/S2667096822000118
  2. Bianchi, C. and Andrews, L. (2018), “Consumer engagement with retail firms through social media: an empirical study in Chile”, International Journal of Retail & Distribution Management, Vol. 46 No. 4, pp. 364-385. https://doi.org/10.1108/IJRDM-02-2017-0035
  3. Health Literacy Innovations LLC, National Survey of Medicaid Guidelines for Health Literacy, 2007 (link).
  4. United Kingdom Financial Conduct Authority, FG22/5 Final non-Handbook Guidance for firms on the Consumer Duty, July 2022 (link) at 8.30 – 8.38.
  5. Eltorai AE, Ghanian S, Adams CA Jr, Born CT, Daniels AH., ‘Readability of Patient Education Materials on the American Association for Surgery of Trauma Website’, Arch Trauma Res. 2014 Apr 30;3(2):e18161. doi: 10.5812/atr.18161. PMID: 25147778; PMCID: PMC4139691 (link), citing Doak CC, Doak LG, Root JH. Teaching Patients with Low Literacy Skills. 2nd ed. Philadelphia, PA: JB Lippincott; 1996.
  6. Australian Government Style Manual, https://www.stylemanual.gov.au/accessible-and-inclusive-content/literacy-and-access#literacy_affects_access_to_government_services_and_informationaccessed 27 September 2023.
  7. National Literacy Trust, https://literacytrust.org.uk/parents-and-families/adult-literacy/what-do-adult-literacy-levels-mean/, accessed 27 September 2023.
  8. Most of the widely used tests such as Flesch-Kincaid Grade Level, Gunning-Fog Index, Fry Method and SMOG method output grade scores based on the United States schooling system. Abid Ismail et al note that “there is a strong need to develop country specific grading mechanism with respect to readability.” (see Abid Ismail et al, Connect the dots: Accessibility, readability and site ranking – An investigation with reference to top ranked websites of Government of India, Journal of King Saud University – Computer and Information Sciences, Volume 31, Issue 4, 2019, Pages 528-540, ISSN 1319-1578, https://doi.org/10.1016/j.jksuci.2017.05.007.(https://www.sciencedirect.com/science/article/pii/S1319157816301550)
  9. United Kingdom Financial Conduct Authority, FG22/5 Final non-Handbook Guidance for firms on the Consumer Duty, July 2022 (link) at 8.13, 8.16.
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