Companies procuring translation services increasingly ask suppliers to prove certification. Two standards come up most often: ISO 17100 and ISO 18587. They are not interchangeable. They cover different processes, and specifying the wrong one in a contract or supplier brief creates practical problems down the line. Understanding what each standard actually covers makes supplier evaluation considerably more straightforward.
What ISO 17100 Covers and When It Applies
ISO 17100:2015 is the reference standard for human translation services. It sets out requirements for the translation workflow, translator and reviser qualifications, and project management procedures. A certified provider must demonstrate documented workflows, translators who meet specific competence criteria, and an independent revision stage. The process is often described as TEP: translation, editing, and proofreading.
The standard applies where translation is entirely human. It is the expected certification for content where accuracy has regulatory, legal, or safety implications: technical documentation, contracts, equipment manuals, instructions for use, safety data sheets, and similar materials. For any technical translation project with formal quality requirements, ISO 17100 certification provides assurance about the process, not merely about the final document.
What the standard does not address is machine translation. Once an MT engine is introduced into the workflow, ISO 17100 is no longer the applicable framework for that part of the process. That is where ISO 18587 becomes relevant.
What ISO 18587 Covers and Where It Fits
ISO 18587:2017 covers the post-editing of machine translation output by human translators. It defines two levels of post-editing: full post-editing and light post-editing. The distinction matters in practice.
Full post-editing requires that the final text meets the same quality standards as a human translation. The post-editor reviews accuracy, fluency, terminology, formatting, and suitability for the target audience. The result should be indistinguishable from a translation produced without MT.
Light post-editing has a narrower objective: making the text comprehensible and factually correct, without requiring stylistic polish. It is appropriate for internal reference content, draft reports, or communications where fluency is not the priority.
ISO 18587 does not replace ISO 17100. It applies to a different process: one in which machine translation is used as a starting point and a qualified human translator intervenes to improve and validate the output. Certification to ISO 18587 means the post-editing process is structured, documented, and carried out by professionals with defined competences.
Choosing the Right Standard for Your Project
The decision depends on content type, volume, intended use, and regulatory or contractual requirements.
- The content carries legal, regulatory, or safety implications
- The client or regulatory body requires documented human translation
- The text will be published, distributed externally, or incorporated into official technical documentation
- Confidentiality requirements exclude the use of external MT engines
- Volume is high and deadlines are tight
- The content is informational and will not be subject to rigorous third-party scrutiny
- MT quality for the relevant language pair is high enough to make post-editing genuinely efficient
- The client explicitly accepts the use of MT in the process
For many projects involving user manual translation, the answer is not exclusively one standard or the other. It is common practice to apply ISO 17100 to critical content (safety warnings, installation instructions, regulatory sections) and ISO 18587 full post-editing to lower-risk content (parts lists, repetitive specification tables). This hybrid approach is increasingly standard on high-volume technical projects.
Language pair is a significant variable. MT quality varies considerably: it is consistently higher for pairs such as English-Spanish than for less-represented pairs. Overlooking this when defining the workflow can undermine the efficiency gains that post-editing is supposed to deliver.
How to Verify a Supplier's Certification
ISO certification is not a self-declaration. It is issued by an accredited certification body, has a defined scope, and carries an expiry date. When evaluating a translation supplier, the following should be requested:
- The original certificate, not just a logo on the website
- The certification scope: which services and language pairs are covered
- The name of the certification body and the date of the most recent renewal
- Evidence of surveillance audits
A supplier who cannot provide this information promptly is not genuinely certified for the relevant contractual purposes.
M21Global: ISO 17100 and ISO 18587 for Technical Projects
M21Global holds ISO 17100:2015 certification (Bureau Veritas) and ISO 18587 certification, which means the right process can be proposed for each project without compromise on quality. With more than 300 million words translated and 20 years of experience in technical translation, the team can assess content type, language pair, and client requirements and recommend the most efficient approach. For large-volume technical projects or projects with specific certification requirements, the starting point is a conversation about the specific scope. Contact M21Global to discuss your project requirements.
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Frequently Asked Questions
What is the difference between ISO 17100 and ISO 18587?
ISO 17100 covers fully human translation services and sets requirements for workflow, translator qualifications, and independent revision. ISO 18587 covers the post-editing of machine translation output by human translators, with two levels: full post-editing and light post-editing.
Can an ISO 17100 certified supplier use machine translation?
ISO 17100 does not regulate the use of machine translation. If a supplier introduces MT into the workflow, ISO 17100 is no longer the applicable framework for that component. The MT-assisted process should be covered under ISO 18587.
Does ISO 18587 guarantee the same quality as ISO 17100?
It depends on the post-editing level applied. Full post-editing under ISO 18587 targets a result equivalent to human translation. Light post-editing has a narrower objective and should not be applied to content with legal, regulatory, or safety implications.
How do I confirm that a supplier is genuinely certified?
Request the original certificate issued by the certification body (such as Bureau Veritas or SGS), check the declared scope and language pairs covered, and verify the renewal date. A logo on a website does not constitute proof of active certification.
Can both standards be applied within the same project?
Yes. On high-volume projects it is common to apply ISO 17100 to critical content and ISO 18587 full post-editing to lower-risk sections. The supplier should document clearly which process applies to each content type.
