ISO 17100 vs ISO 18587: Which Standard Does Your Agency Need?

The translation industry operates at the intersection of human expertise and advancing technology. On one side, professional human translators deliver nuanced, contextually accurate translations. On the other, machine translation engines produce increasingly capable output that still requires human refinement. Two international standards have emerged to govern quality in each approach: ISO 17100 for human translation services and ISO 18587 for machine translation post-editing (MTPE).

For language service providers navigating the certification landscape, understanding the differences between these two standards — and knowing which one your agency needs — is a critical strategic decision. This guide provides a comprehensive comparison to help you make the right choice.

ISO 17100: The Human Translation Standard

ISO 17100:2015 — "Translation services — Requirements for translation services" — is the internationally recognized standard that defines requirements for the delivery of quality translation services performed by human translators. It replaced the earlier European standard EN 15038 and has become the benchmark for translation quality worldwide.

Scope and Coverage

ISO 17100 covers the entire translation service lifecycle, from client inquiry through final delivery and post-project activities. It addresses:

• Translator qualifications: Formal education requirements (recognized degree in translation, linguistics, or equivalent), plus demonstrated competence in source and target languages
• Translation competencies: Translating competence, linguistic and textual competence, research competence, cultural competence, technical competence, and domain competence
• Process requirements: Mandatory translation, revision (by a second qualified linguist), and optional review steps
• Project management: Client specifications analysis, feasibility assessment, project preparation, and production workflows
• Technology and resources: Translation memory management, terminology databases, and quality assurance tools
• Post-delivery: Client feedback handling, corrective actions, and continuous improvement

Who Is ISO 17100 For?

ISO 17100 is designed for any organization that provides human translation services. This includes translation agencies, localization companies, in-house translation departments, and freelance translators working within a structured framework. It is particularly relevant for agencies serving regulated industries such as legal, medical, pharmaceutical, and financial services.

ISO 18587: The Machine Translation Post-Editing Standard

ISO 18587:2017 — "Translation services — Post-editing of machine translation output — Requirements" — addresses the quality requirements for the process of post-editing machine translation (MT) output. As MT technology has matured, this standard provides the framework for ensuring that machine-translated content meets professional quality expectations after human editing.

Scope and Coverage

ISO 18587 specifically focuses on the post-editing phase — the human review and correction of text that has been initially translated by a machine translation engine. It covers:

• Post-editor competencies: Language proficiency, translation skills, ability to work with MT output, understanding of MT strengths and weaknesses, and domain knowledge
• Two levels of post-editing: Light post-editing (comprehensible output) and full post-editing (comparable to human translation quality)
• Process requirements: Pre-production assessment of MT suitability, post-editing guidelines, and quality checking procedures
• MT engine management: Requirements for selecting, training, and maintaining MT systems
• Client communication: Setting expectations about MT-based workflows and post-editing levels
• Quality evaluation: Metrics and methods for assessing post-edited output quality

Who Is ISO 18587 For?

ISO 18587 is designed for organizations that use machine translation as part of their service delivery. This includes agencies offering MTPE as a distinct service tier, technology companies with MT-driven localization pipelines, and LSPs integrating neural machine translation into their workflows. It is especially relevant for high-volume, time-sensitive content types such as user-generated content, technical documentation, and e-commerce product descriptions.

Side-by-Side Comparison

Aspect	ISO 17100	ISO 18587
Primary Focus	Human translation services	Post-editing of machine translation output
Published	2015	2017
Initial Translation	Performed by qualified human translator	Performed by machine translation engine
Key Human Role	Translator + Revisor	Post-editor
Qualification Requirements	Degree in translation/linguistics or equivalent + 5 years experience	Translation competence + MT-specific skills + domain knowledge
Quality Levels	Single standard of quality (professional translation)	Two levels: light post-editing and full post-editing
Mandatory Revision	Yes — by a second qualified linguist	Quality checking required; full revision recommended for full PE
Technology Requirements	TM, terminology tools, QA tools	MT engine management, PE tools, quality metrics
Best For	Creative, legal, medical, marketing content	High-volume technical, e-commerce, user content
Client Expectation	Publication-ready human quality	Varies by PE level (comprehensible to publication-ready)

Key Differences Explained

1. Human Translation vs Machine Translation Post-Editing

The most fundamental difference between the two standards is the origin of the initial translation. Under ISO 17100, a qualified human translator creates the translation from scratch, bringing cultural understanding, creative judgment, and contextual awareness to every sentence. Under ISO 18587, a machine translation engine produces the initial output, and a human post-editor then corrects, refines, and improves that output.

This distinction has significant implications for the types of content each standard is best suited for. Creative content, marketing copy, legal documents, and sensitive communications typically require the nuanced understanding that only human translation provides. Conversely, high-volume technical documentation, product listings, and knowledge base articles often benefit from the speed and cost efficiency of MTPE workflows.

2. Translator Qualifications vs Post-Editor Qualifications

ISO 17100 sets rigorous qualification requirements for translators: a recognized higher education degree in translation, linguistics, or an equivalent field, or alternatively, a degree in another field plus a minimum of five years of documented professional translation experience. Revisors must meet the same qualifications plus have revision experience.

ISO 18587 takes a different approach to post-editor qualifications. While post-editors must possess translation competence and linguistic skills, the standard also requires specific competencies related to working with MT output. Post-editors need to understand how MT engines work, recognize common MT error patterns, and know when to edit versus retranslate entirely. This is a distinct skill set that overlaps with but differs from traditional translation competence.

3. Process Requirements

The process workflows differ significantly between the two standards:

ISO 17100 mandates a translate-revise workflow as a minimum, where every translation must be revised by a second qualified linguist. ISO 18587 requires quality checking of post-edited output but provides more flexibility in how that quality assurance is structured.

ISO 17100's process is linear and well-defined: translate, revise, optionally review, deliver. ISO 18587 introduces additional upfront steps, including assessing whether a given content type is suitable for MT processing, selecting the appropriate MT engine, and determining the required post-editing level (light or full) before work begins.

4. Quality Benchmarks

ISO 17100 establishes a single quality benchmark: professionally translated, revised content ready for its intended purpose. There is no concept of "tiers" of quality — all output should meet the same professional standard.

ISO 18587 introduces a dual-quality framework. Light post-editing aims to produce comprehensible, accurate output that conveys the correct meaning, even if the style is not polished. Full post-editing aims for quality comparable to human translation, where the output reads naturally and meets the same expectations as a human-translated text. This flexibility allows agencies to offer different service levels at different price points.

Which One Do You Need? A Decision Framework

The choice between ISO 17100 and ISO 18587 depends on your agency's service portfolio, client base, and strategic direction. Here is a practical framework to guide your decision.

Can You Get Both? Yes — and Here Is Why You Should

The good news is that ISO 17100 and ISO 18587 are not mutually exclusive. In fact, holding both certifications positions your agency as a versatile provider that can deliver quality across the full spectrum of translation approaches. Here is why dual certification makes strategic sense:

• Complete market coverage: You can respond to any RFP, whether it requires traditional human translation or MT post-editing capabilities
• Client flexibility: Offer clients a choice of service tiers, from premium human translation to cost-effective MTPE, all backed by certified quality processes
• Future-proofing: As the industry continues its shift toward hybrid workflows combining human and machine translation, having both certifications ensures you are prepared
• Operational efficiency: The two standards share common elements in project management, quality assurance, and documentation. Implementing one makes the second easier to achieve
• Competitive advantage: Very few agencies hold both certifications, making dual certification a powerful differentiator

Getting Certified with TranslationCert

Whether you choose ISO 17100, ISO 18587, or both, the certification process with TranslationCert is designed to be straightforward and efficient. Here is how it works:

1. Free readiness assessment: Start with a complimentary evaluation at baltum.ai to understand your current compliance level against the chosen standard(s)
2. Gap analysis: Our certification experts identify specific areas that need attention and provide actionable recommendations
3. Documentation support: Access templates and guidance for creating the required documentation, from quality manuals to process descriptions
4. Online audit: Complete your certification audit remotely through our digital platform — no on-site visits required
5. Certificate issuance: Upon successful completion, receive your ISO certificate, typically within two to four weeks from the start of the process

For agencies pursuing dual certification, we offer a combined assessment process that evaluates both standards simultaneously, saving time and reducing costs compared to separate audits.

The Bottom Line

ISO 17100 and ISO 18587 serve different but complementary purposes in the translation industry. ISO 17100 is the essential standard for agencies delivering human translation services — it is the most widely recognized, most frequently required, and most broadly applicable certification for LSPs. ISO 18587 is the right choice for agencies with significant MTPE operations, providing a quality framework specifically designed for machine-assisted translation workflows.

For most agencies, ISO 17100 should be the first certification to pursue. It covers the broadest range of client requirements and provides the strongest market positioning. Once ISO 17100 is in place, adding ISO 18587 becomes a natural extension for agencies that incorporate MT into their service offerings.

The agencies that will thrive in the evolving translation landscape are those that can demonstrate certified quality across both human and machine-assisted workflows. Dual certification is not just a badge — it is a strategic investment in your agency's future.

Not sure which standard is right for your agency?
Take a free readiness assessment at baltum.ai or request a consultation with our certification experts. We will help you determine the best certification path for your specific business needs.