Key takeaways
- MTPE combines machine translation output with correction by a human post-editor, and is governed by its own standard, ISO 18587.
- Light post-editing fixes meaning and comprehension errors; full post-editing also fixes style, grammar and terminology so the text can be published.
- Nimdzi's UK pricing study for the ATC found an average MTPE price of £0.079 per word from English, with discounts ranging from 0 to 80% of the full rate depending on editing effort.
- MTPE output quality is capped by the raw machine output, so it suits repetitive, factual content far better than marketing, legal or safety-critical text.
- Raw machine translation followed by post-editing is outside the scope of ISO 17100, the main standard for human translation services.
This guide is for buyers who have been offered machine translation post-editing as a cheaper or faster alternative to human translation, and want to know what they are getting. It explains how MTPE works, the two levels of post-editing, the relevant ISO standard, what it costs and where it should not be used.
It differs from our older article Humans vs Machines, which discusses why language needs human judgement; this guide covers the practical hybrid workflow.
What is machine translation post-editing?
Machine translation post-editing (MTPE) is the process of a qualified linguist reviewing and correcting text that has first been translated by a machine translation engine. The post-editor compares each machine-translated sentence with the source, fixes errors and decides what can stay. The result is a human-checked translation produced from a machine draft rather than from a blank page.
MTPE has its own international standard. The ISO catalogue entry for ISO 18587:2017 states that the standard “provides requirements for the process of full, human post-editing of machine translation output and post-editors' competences.” ISO lists the standard as due for revision, and the draft successor is titled “Post-editing of non-human translation output”, a broader title that is not limited to machine translation engines.
What is the difference between light and full post-editing?
Light and full post-editing differ in the quality target. The industry body TAUS distinguishes between “good enough” quality and quality “similar or equal to human translation”, which a 2025 review in Frontiers in Artificial Intelligence notes “almost correspond to “light” and “full” post-editing, respectively”.
| Aspect | Light post-editing | Full post-editing |
|---|---|---|
| Goal | Accurate and understandable | Publishable, close to human translation |
| Meaning errors | Corrected | Corrected |
| Terminology | Critical terms only | Fully consistent with glossary |
| Grammar and style | Left if understandable | Corrected to natural target-language style |
| Typical use | Internal knowledge bases, large archives, gisting | Customer-facing help content, product data, manuals |
Always confirm in writing which level a quote includes. A low MTPE price usually means light post-editing, which is not suitable for anything customers will read.
How much does MTPE cost compared with human translation?
MTPE is usually priced below full human translation because the post-editor starts from a draft. The UK Language Services Pricing Study 2020 by Nimdzi Insights, published by the Association of Translation Companies (ATC), found:
- an average MTPE price from English of £0.079 per word, irrespective of domain or language pair;
- discounts on the full word rate ranging from 0 to 80%, depending on the level of editing required;
- MTPE as the most common machine-translation-related service among UK providers.
For comparison, the same study reported average human translation rates from English of £0.120 to £0.157 per word, depending on language group. The wider pricing picture is explained in translation cost per word in the UK.
How does an MTPE workflow work?
A controlled MTPE workflow includes checks before and after the machine step. A typical sequence is:
- Suitability check. The provider tests a sample to see whether the machine output for this language pair and subject is good enough to edit.
- Preparation. Glossaries and existing translation memories are applied so approved terminology is used.
- Machine translation. The text is processed by an engine the client has approved for confidentiality.
- Post-editing. A native-speaking linguist edits to the agreed level, light or full.
- Quality check. Automated checks for numbers, tags and terms, plus a sample review; see how translation quality assurance works.
Which content suits MTPE, and which does not?
MTPE suits high-volume, repetitive, factual text in well-supported language pairs, and is a poor fit for creative, legal, medical and low-resource-language content. In short: the more the text depends on nuance, persuasion or precise legal effect, the less the machine draft helps.
- Usually suitable: product specifications, internal knowledge bases, support articles, large document archives for review.
- Use with caution: technical manuals and e-learning, where safety warnings and terminology must be checked by a specialist.
- Usually unsuitable: marketing slogans and campaigns, contracts and court documents, patient-facing medical content, and languages for which machine engines have little training data.
Sector-specific risks are covered in machine translation for legal documents and machine translation in healthcare.
Is MTPE the same as human translation under ISO 17100?
No. The ISO catalogue entry for ISO 17100:2015, the requirements standard for translation services, states that “The use of raw output from machine translation plus post-editing is outside the scope of ISO 17100:2015.” The Association of Translation Companies reports in its article on the planned revision of ISO 17100 that whether post-editing should be equated with revision is still being debated. The difference between these standards is explained in ISO 17100 vs ISO 9001.
Common mistakes when buying MTPE
Most MTPE disappointments come from unclear expectations about the quality level. Avoid these mistakes:
- Not specifying light or full. The cheapest offer is usually the lightest edit.
- Skipping the sample test. Poor machine output can take longer to fix than translating from scratch.
- Ignoring confidentiality. Ask which engine is used and whether your text is stored or used for training.
- Using MTPE for persuasive text. Edited machine output tends to follow the source structure closely, which reads flatly in marketing copy.
- Expecting the same price on every language pair. Engine quality varies widely between languages.
For how MTPE fits into the wider buying decision, see how to choose a translation agency and the comparison of agency, freelancer and machine translation.
How TranslationWorks can help
TranslationWorks is a UK-based translation agency that provides professional human translation by native-speaking linguists in 150+ languages, and holds ISO 17100 certification, ISO 9001 and ISO 27001 registration. If you are deciding between human translation and a machine-assisted workflow, tell us what the content is, who will read it and how it will be used, and we will confirm what we can provide in your free quote. Our translation services cover legal, medical, technical, e-commerce and marketing content, and non-standard workflows can be discussed through our custom language services. Request a free quote within 24 hours.
