Machine translation has undergone a revolution. The rise of neural machine translation (NMT) engines — powered by large language models and trained on billions of sentence pairs — has transformed MT output from laughably bad to remarkably good. For many content types and language pairs, raw MT output now achieves fluency scores that would have been unimaginable just five years ago. Yet despite these advances, a persistent trust gap remains between what MT can deliver and what clients are willing to accept.
This trust gap is the central challenge facing the machine translation post-editing (MTPE) market. Clients know that MT is faster and cheaper than human translation. They want to benefit from those efficiencies. But they worry about quality, consistency, and accountability. Who is responsible when MT-generated content contains errors? How can they be sure that post-editing was thorough enough? What quality guarantees can an LSP actually provide for MTPE work?
ISO 18587 was created specifically to answer these questions. As the international standard for post-editing of machine translation output, it provides a framework that gives both LSPs and their clients confidence in MTPE quality. For agencies looking to grow their MTPE business, understanding and implementing this standard is becoming essential.
The Rise of MTPE in the Translation Industry
The numbers tell a compelling story. Industry analysts estimate that MTPE now accounts for over 25% of all translation volume processed by major LSPs, up from less than 5% a decade ago. The market for MTPE services is growing at roughly three times the rate of traditional human translation. And the trend is accelerating as MT engines continue to improve and clients become more comfortable with the technology.
This growth is being driven by several converging factors. Content volumes are exploding — the average enterprise now produces 10 times more translatable content than it did in 2015. Simultaneously, time-to-market pressures are intensifying, with product launches, marketing campaigns, and regulatory filings all demanding faster turnaround. Traditional human translation workflows simply cannot scale to meet these demands at the speed and cost points clients require.
MTPE offers a middle path: faster and more cost-effective than pure human translation, while significantly higher quality than raw MT output. For many content types — technical documentation, knowledge base articles, product descriptions, internal communications — MTPE delivers an optimal balance of quality, speed, and cost.
Client Concerns About MT Quality
Despite the clear efficiency benefits, many clients remain hesitant to adopt MTPE workflows. Their concerns are legitimate and worth understanding, because ISO 18587 certification directly addresses each of them.
Quality Consistency
MT output quality varies significantly depending on language pair, domain, content type, and the specific MT engine used. A system that produces excellent results for English-to-Spanish technical content may perform poorly for English-to-Japanese marketing copy. Clients worry that without robust quality controls, MTPE output quality will be unpredictable from project to project.
Post-Editor Competence
Post-editing is not the same as translation or revision. It requires a specific skill set that combines linguistic expertise with an understanding of MT error patterns. Clients worry that their LSP may assign post-editing work to linguists who lack the training and experience needed to effectively correct MT output. An undertrained post-editor may miss systematic MT errors or, worse, introduce new errors while editing.
Accountability and Transparency
When a client receives a translation from a human translator, the accountability chain is clear. But when content passes through an MT engine and then a post-editor, questions arise. How much of the final output is machine-generated versus human-edited? What quality checks were performed? Can the client trust that the post-editor actually reviewed every segment, or did they simply skim through and approve the MT output with minimal changes?
A localization director at a Fortune 500 technology company explained the dilemma: "We want to use MTPE because the cost savings are significant. But we need to know that the quality is genuinely comparable to human translation for the content types we're using it for. ISO 18587 gives us that confidence."
What ISO 18587 Guarantees
ISO 18587:2017 establishes requirements for the process of post-editing machine translation output. It provides a comprehensive framework covering every aspect of the MTPE workflow, from pre-production assessment through delivery and quality evaluation. Here is what the standard requires.
Pre-Production Requirements
Before any post-editing work begins, ISO 18587 requires a systematic assessment of whether MTPE is appropriate for the specific project. This includes evaluating the MT engine's suitability for the language pair and domain, assessing the quality of the source content (since poorly written source text produces poor MT output), determining whether full or light post-editing is appropriate for the client's intended use, and agreeing on quality specifications and acceptance criteria with the client.
This pre-production assessment is critical because it prevents the most common source of MTPE quality failures: using MT for content types or language pairs where the technology is not yet mature enough to deliver acceptable results even after post-editing.
Post-Editor Competence Requirements
ISO 18587 defines specific competence requirements for post-editors that go beyond standard translator qualifications. Post-editors must demonstrate linguistic competence in both the source and target languages equivalent to a qualified translator, research competence including the ability to efficiently identify and resolve MT-specific error types, understanding of MT technology including knowledge of how MT engines work, common error patterns for different engine types, and the limitations of current MT technology, domain expertise appropriate to the content being post-edited, and post-editing skills including the ability to work efficiently with MT output, make appropriate corrections without over-editing, and maintain consistency across segments.
Post-Editor vs. Translator: Key Differences
A qualified translator is not automatically a qualified post-editor. Post-editing requires additional skills: the ability to recognize systematic MT errors, the discipline to correct only what needs correction (avoiding unnecessary changes that increase cost without improving quality), and the mental flexibility to work with existing text rather than creating translations from scratch. ISO 18587 recognizes these distinctions and requires specific training and assessment for post-editors.
Full vs. Light Post-Editing
One of the most important contributions of ISO 18587 is its clear definition of two distinct levels of post-editing, each with specific quality targets and use cases.
Full Post-Editing
Full post-editing aims to produce output that is comparable in quality to human translation. The post-editor must ensure that the content is semantically correct, grammatically accurate, uses appropriate terminology, follows the conventions of the target language, and is stylistically appropriate for the intended audience. Full post-editing is suitable for content that will be published externally, used in marketing, or reviewed by end users who expect polished, natural-sounding text.
From a practical standpoint, full post-editing typically achieves 30–40% productivity gains over translation from scratch, while delivering quality that is indistinguishable from human translation to the end reader.
Light Post-Editing
Light post-editing aims to produce output that is accurate and understandable, but may retain some stylistic characteristics of MT output. The post-editor focuses on ensuring semantic accuracy, correcting critical grammatical errors, and verifying terminology, but does not aim for the same level of stylistic polish as full post-editing. Light post-editing is appropriate for content intended for internal use, gisting purposes, or situations where the primary goal is comprehension rather than publication quality.
Light post-editing typically achieves 50–70% productivity gains, making it significantly more cost-effective than full post-editing or human translation.
Choosing the Right Level
ISO 18587 requires that the level of post-editing be explicitly agreed upon with the client before work begins. This transparency is essential for managing expectations and ensuring that the client receives output that matches their intended use. A common source of client dissatisfaction with MTPE services is the mismatch between expectations and delivery — a client expecting publication-quality output but receiving light post-editing. The standard's clear definitions and agreement requirements eliminate this confusion.
How Certification Builds Client Confidence
ISO 18587 certification provides clients with verifiable assurance across several critical dimensions of MTPE quality.
Process Transparency
Certified agencies have documented procedures for every step of the MTPE workflow. Clients can review these procedures and understand exactly how their content will be processed, who will work on it, and what quality checks will be performed. This transparency transforms MTPE from a "black box" into a well-understood, predictable process.
Qualified Post-Editors
Certification requires that agencies maintain records of post-editor qualifications, training, and performance assessments. Clients can be confident that the individuals editing their content have the specific skills and experience required for quality post-editing, not just general translation ability.
Quality Metrics and Reporting
ISO 18587 requires agencies to monitor and measure MTPE quality through defined metrics. This means that certified agencies can provide clients with objective quality data, not just subjective assurances. Quality trends can be tracked over time, enabling data-driven decisions about when MTPE is working well and when adjustments are needed.
Continuous Improvement
The standard requires a feedback loop where post-editing insights are used to improve MT engine performance and post-editing processes. For clients, this means that quality improves over time as the agency refines its MT engines, terminology resources, and post-editing guidelines based on real project data.
MTPE Pricing Models and Certification
One of the practical benefits of ISO 18587 certification is that it enables more sophisticated and transparent pricing models for MTPE services. The clear distinction between full and light post-editing allows agencies to offer tiered pricing that reflects the actual effort involved.
Common MTPE pricing approaches include per-word rates based on post-editing level, where full post-editing is typically priced at 60–70% of human translation rates and light post-editing at 30–50%. Some agencies use hourly rates based on actual post-editing time, which can be more equitable when MT quality varies between projects. Others employ a hybrid model that combines a base per-word rate with time-based adjustments for particularly challenging content.
ISO 18587 certification supports these pricing models by providing a common vocabulary and shared understanding between agency and client about what each service level entails. When both parties understand the difference between full and light post-editing, pricing discussions become more straightforward and expectations are more easily aligned.
Combining ISO 18587 with ISO 17100
For agencies offering both traditional human translation and MTPE services, holding dual certification in ISO 17100 and ISO 18587 provides comprehensive coverage. ISO 17100 certifies your human translation processes, while ISO 18587 certifies your MTPE workflows. Together, they demonstrate to clients that your agency maintains high quality standards regardless of the production methodology used.
The comparison between these two standards is particularly relevant for agencies developing their service portfolio. Many clients appreciate working with a single agency that can offer both services under certified quality processes, selecting the optimal approach for each project based on content type, budget, and timeline.
Getting Started with ISO 18587 Certification
For agencies already offering MTPE services, the path to ISO 18587 certification begins with formalizing and documenting the processes you likely already follow. Key steps include assessing your current MTPE workflows against the standard's requirements using a free readiness assessment at baltum.ai, documenting your post-editor qualification criteria and assessment procedures, formalizing your pre-production assessment process for determining MTPE suitability, establishing quality metrics and monitoring procedures, and creating clear service level definitions for full and light post-editing.
For agencies new to MTPE, certification provides a roadmap for building MTPE capabilities from the ground up, ensuring that quality processes are embedded from the start rather than retrofitted later.
Conclusion: Trust Is the Currency of MTPE Growth
The MTPE market will continue to grow rapidly as MT technology improves and content volumes increase. But growth in this market depends fundamentally on client trust. Clients need to believe that MTPE output meets their quality requirements before they will commit significant volumes to this workflow.
ISO 18587 certification is the most powerful tool available for building that trust. It transforms MTPE from an opaque, anxiety-inducing proposition into a transparent, quality-assured service that clients can evaluate, compare, and commit to with confidence. For LSPs, certification is not just about quality management — it is about unlocking the growth potential of one of the fastest-moving segments in the translation industry.
Ready to explore ISO 18587 certification for your agency?
Start with a free readiness assessment at baltum.ai or request a quote from TranslationCert. Our experts will help you build certified MTPE processes that win client confidence.