Learn what the ISO 24495 plain language standard is, how to apply it, its relationship with easy-to-read guidelines, IFLA guidelines, and Inclusion Europe directives. Complete guide with practical examples.
ENGLISH VERSION
What is ISO 24495 and why should you care?
Have you ever read an official document and felt like you needed a dictionary, a lawyer, and an aspirin to understand it? You are not alone. According to the Center for Plain Language, more than 60% of adults struggle to understand administrative and legal texts. That is not a people problem—it is a writing problem.
ISO 24495, published in June 2023 under the official title “Plain language — Part 1: Governing principles and guidelines,” is the first international standard that defines what plain language is and how to apply it systematically. It was developed by ISO Technical Committee TC 37, with input from organizations such as PLAIN (Plain Language Association International), Clarity International, and the Center for Plain Language.
Personally, I believe this standard marks a turning point. For decades, plain language has been a well-intentioned recommendation. Now it has international technical backing. Think of it like going from “let me just explain it to you informally” to “here is a manual with precise instructions.”
The 4 core principles of ISO 24495
The standard organizes plain language around four principles that you can apply to any text, from a contract to an email:
1. Relevant: write for your reader
The first principle states that communication must be relevant to the reader. Sounds obvious? Maybe, but think about it: how many times have you received a document packed with information you did not need, while the information you actually needed was missing? ISO 24495 asks you to identify your audience, understand their context, and select only the information they truly need.
2. Findable: logical structure
The second principle requires that the reader can find what they are looking for. This means using clear headings, lists, tables, and a logical organization. It is like the difference between a supermarket with labeled aisles and one where products are piled up randomly.
3. Understandable: clear words and sentences
This is where many texts fail. The standard recommends using words your audience knows, short sentences (ideally 15–20 words), active voice, and avoiding unnecessary jargon. It is not about dumbing things down—it is about respecting your reader’s time and cognitive capacity.
4. Usable: the reader can act
The fourth principle closes the loop: after reading the text, can the reader do what they need to do? Can they fill out the form, make the decision, follow the instructions? If the answer is no, the text is not doing its job, no matter how well it is written.
ISO 24495 vs. easy-to-read: are they the same?
This is a question I get all the time, and the short answer is: no, but they complement each other. Plain language and easy-to-read share the goal of making communication accessible, but they target different audiences and involve different levels of adaptation.
| Feature | Plain language (ISO 24495) | Easy-to-read |
|---|---|---|
| Target audience | General population | People with intellectual disabilities, reading difficulties |
| Level of simplification | Moderate: common vocabulary, short sentences | High: basic vocabulary, one idea per sentence |
| Visual elements | Optional (tables, lists) | Mandatory (supporting images) |
| Reference standard | ISO 24495-1:2023 | IFLA guidelines, Inclusion Europe directives, UNE 153101:2018 (Spain) |
| Validation | User testing recommended | Validation with people with intellectual disabilities required |
IFLA guidelines and Inclusion Europe directives for easy-to-read
If you are specifically interested in easy-to-read content, two international references stand out. The IFLA Guidelines for Easy-to-Read Materials recommend sentences of 5 to 15 words, one idea per sentence, concrete language (avoiding metaphors and abstractions), and images that reinforce the message.
Inclusion Europe’s “Information for All” guidelines are the European benchmark for creating easy-to-read content. They emphasize the participation of people with intellectual disabilities in validating texts and the use of pictograms and simple language. In Spain, AENOR published the UNE 153101:2018 standard, which was the first national easy-to-read standard in the world.
Personally, I think the ideal path is to combine both approaches: apply ISO 24495 as the baseline for all communication and create easy-to-read versions for those who need them. They are not competitors; they are complementary layers of communicative accessibility.
How to implement ISO 24495 in your organization
Implementing plain language does not require rewriting everything overnight. Here is a practical roadmap:
- Step 1: Identify your critical documents (contracts, forms, legal notices, citizen communications).
- Step 2: Analyze them using the 4 principles of ISO 24495 as a checklist.
- Step 3: Rewrite prioritizing clarity. Use tools like the Flesch Reading Ease score or Hemingway Editor.
- Step 4: Test with real users from your target audience.
- Step 5: Establish an internal style guide based on the standard.
- Step 6: Train your team. PLAIN and Clarity International offer courses and certifications.
Key data and figures
| Data point | Source |
|---|---|
| 46% of Spanish adults have low reading comprehension levels | PIAAC-OECD 2023 |
| Plain language documents reduce inquiries by 25–50% | Center for Plain Language |
| ISO 24495-1 was voted on by 23 ISO member countries | ISO/TC 37 |
| Clarity International has members in more than 50 countries | Clarity International |
| UNE 153101 is the first national easy-to-read standard in the world | AENOR |
Frequently Asked Questions
Everything you need to know.
01
No, ISO 24495 is a voluntary standard. However, its adoption is growing rapidly. In some countries, transparency and consumer rights laws already require clear communications, and this standard provides the technical framework to meet those obligations.
02
WCAG 2.1, in its criterion 3.1.5 (Level AAA), recommends that text be understandable for people with a secondary education. ISO 24495 provides concrete tools to achieve that goal. Additionally, WCAG guideline 3.1 focuses on making content readable and understandable, which connects directly with plain language principles.
03
No. Although Part 1 focuses on written communication, the principles are applicable to any format: videos, digital interfaces, online forms, signage. ISO is working on future parts that will address other formats.
04
The IFLA guidelines are practical international recommendations aimed at libraries and publishers. Inclusion Europe’s “Information for All” directives are the European reference, with a strong emphasis on validation by people with intellectual disabilities. Both complement each other and can be used together.
05
You can purchase ISO 24495-1:2023 directly from the ISO online store (iso.org) or through your national standards body. The document is approximately 16 pages long and costs around 60 CHF (Swiss francs).
06
Currently, no tool can automatically certify full compliance with the standard, as much of the evaluation requires human judgment. However, tools like Hemingway Editor, readability indices, and user testing can help you approach the standards.
07
The Center for Plain Language, based in the United States, is one of the leading organizations promoting plain language worldwide. It awards the annual ClearMark Awards for exemplary plain language documents and the WonderMark Awards for the worst offenders. Its research and advocacy were instrumental in shaping ISO 24495.
