Compare the translation against the source, not against your sense of how natural it sounds. A fluent sentence can still carry a wrong date, a dropped digit or a respelled surname. The most reliable method is a dedicated fact pass: mark every name, date, number and unit in the source, then confirm each one appears, unchanged in meaning, in the translation. When an error would be costly, have a skilled human translator revise the text.
Why the source text is the only judge
The European Commission defines revision as a bilingual comparison of source and translation for accuracy and completeness. That is the right model for checking AI output: read the translation next to the original, not on its own. A monolingual read-through tells you whether the text is clear. It cannot tell you whether a detail changed or went missing.
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The steps below are an editorial workflow built on that principle. They are not based on a measured error rate. No published statistic for how often AI translation gets names, dates or numbers wrong turned up in the official sources behind this guide, so treat any specific percentage you see elsewhere with suspicion unless it names the language pairs, text types, method and year.
The fact-check pass, step by step
- Set up side by side. Keep the source and translation visible together, for example in two columns or two windows. Read once for meaning first.
- Mark the facts in the source. Highlight every person, organization, place, product, date, time, amount, measurement, percentage, identifier and quantity.
- Find each one in the translation. Confirm the item is present and refers to the same thing. Missing items matter as much as altered ones, because the Commission’s revision check covers completeness as well as accuracy.
- Check names, dates and numbers as three separate passes. Each fails in a different way (see below), so a single combined skim misses things.
- Handle formatting separately. Decide whether a difference is a legitimate locale convention or a changed fact.
- Escalate by risk. If the stakes justify it, send the text to a qualified reviewer.
Checking names
What to compare
- Spelling of every letter, including accents, cedillas, ligatures and other special marks.
- Whether a person, company, product or place name was translated, transliterated or altered when it should stay as written.
- Whether abbreviations and organization names match the organization’s own usage.
What the style guidance says
ISO’s house style tells writers to “follow the spelling of proper nouns and words from foreign languages, including accented letters, cedillas, ligatures or other special marks and any alphabetical forms that do not normally occur in English.” It also says organization names and their abbreviations “shall be written as used by those organizations.” This is style guidance for ISO’s own documents, but it is a sound default for any text where names must be recognizable.
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When the source spelling looks doubtful, verify against the entity’s official website or documents rather than trusting either version. Some names are legitimately rendered differently in the target language (well-known place names, for instance), so check the style your document follows.
Checking dates
- Compare the actual day, month and year with the source, one component at a time.
- Check weekday-and-date pairs, time zones, and ranges (start and end).
- If the target uses a different order or separator, check that against the target locale’s convention. A changed display is not by itself a changed date.
The ambiguous case is a numeric date such as 03/04/2026, which different locales read as 3 April or March 4. When the source is ambiguous, resolve it from context or ask the author before accepting any translation. Where you control the output, writing the month as a word removes the risk.
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Checking numbers and units
Treat each quantity as a complete expression and compare these elements:
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1Repair Windows errors before they cause bigger problems2Scan for outdated or missing drivers - takes under a minute3Clear out junk files and repair common Windows errors| Element | What to confirm |
|---|---|
| Digits | Same digits in the same order; nothing dropped or transposed |
| Sign | Positive or negative, increase or decrease preserved |
| Decimal position and grouping | Separators follow the intended locale and the value is unchanged (1,234 and 1.234 can mean very different things depending on convention) |
| Unit and scale | Same unit, or a correct conversion; thousand, million and billion not confused |
| Currency | Same currency, symbol and amount together |
| Percentages and ranges | Percent versus percentage points; both ends of a range kept |
NIST recommends Arabic numerals and unit symbols for quantity values so they are widely understood. That is technical-writing guidance rather than a rule for every genre, but it is a good choice when numbers must survive translation. Spelled-out numbers in running text (“two thirds”) are easy to overlook, so include them in your marking pass.
Do not silently accept unit conversions. If the translation converts miles to kilometres or one currency to another, check the arithmetic and whether the conversion was wanted at all.
Terminology and reference resources
For specialist vocabulary, use a language-specific style guide or terminology resource. The Commission lists IATE and the DGT Translation Memory among its professional resources. They support terminology consistency, and DGT-TM can also serve machine-translation research or testing. They help you choose the right term, but they do not prove that a particular fact in your text was translated correctly.
Does a second machine translation help?
It can flag disagreements worth examining: if two systems render a date or figure differently, look at that spot first. But agreement is not verification, because both could be wrong in the same way. The official pages reviewed give no guarantee that tools validate each other, so use this only as a pointer to where to look, with the source as the final check.
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Choosing the right level of review
The Commission says the potential impact and likelihood of errors should be assessed, and that higher-risk texts call for more experienced translators and more extensive quality checks. Its eTranslation page states: “If you need a perfectly accurate, high-quality translation, the text still needs to be revised by a skilled professional translator.”
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| Situation | Suggested approach |
|---|---|
| Low stakes, you only need the gist (an informal message, a menu) | Quick personal check of names, dates and numbers against the source |
| Moderate stakes (business correspondence, itineraries, invoices) | Full three-pass fact check; have a bilingual colleague confirm anything doubtful |
| High consequence (legal, medical, financial, safety, official filings) | Skilled professional revision by someone who reads both languages and knows the subject |
What to look for in a reviewer
- Both languages: they must be able to compare source and target, not just read the target.
- Subject knowledge: they should understand the field’s terminology.
- Type of review: the Commission distinguishes bilingual revision (accuracy and completeness) from review, which is a monolingual check of clarity and tone. For fact preservation you need revision.
- Terminology and locale guidance: they should have, or be given, the relevant glossary and target-locale conventions.
A note on tool availability
The Commission describes eTranslation as a neural machine translation tool trained on EU professional translation data. It is offered to eligible users, with exceptions and eligibility conditions, and it supports the 24 official EU languages plus others listed on its service pages. That figure describes language coverage, not accuracy. Other tools differ in languages and access, so none of the advice here assumes any particular one.
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