Reading time: 6 mins

Difference between forwards and back translation

A reverse translation, often referred to as back translation, is the translation of a previously translated document or material back into the initial source language. For example, a Slovenian translation of an English document is translated back into English, i.e. EN>SI>EN. Back translation is often used to check the quality of a translation and highlight discrepancies in meaning between the source and target texts. While both translation processes aim for accuracy, a back translation differs from a “normal” or forward translation because a translated text is used as the source text.

In most cases, a translator who was not involved in the initial translation process does the reverse translation. The translator usually does not have access to the original document. This enables them to evaluate the quality of the translated text as a whole rather than focusing on details like sentence structure or preferred word choices.

The tasks of a reverse translator

  1. The translator translates the translation back into the original source language.
  2. They compare the original source text to the back translation and compile a comparison report.
  3. They check that the initial translation makes sense in the same way as the original source text.
  4. They make a note of any problems that could compromise the overall quality of the initial translation.
  5. They advise the initial translator and client on the necessary changes to the initial translation or any parts that may require additional revision.

Many inaccurate assumptions surround reverse translation: such as the idea that the wording should be identical to the original source text, and that any discrepancies are a sign of mistranslation by the initial translator. If the back translation and original source text are identical, this does not mean that the initial translation was perfect.

Machine translation is often used for back translations. In other cases, another linguist performs steps 2 to 5 as part of a larger team.

Regardless of how the back translation is performed, the real goal is to identify meaningful distinctions between the original source text and the back translation, such as changes in meaning, function, and impact of the text.

Domains that make use of back translation

In the world of clinical trials, most ethics committees and institutional review boards (IRBs) require that back translations and/or certificates of accuracy be submitted with all translated documents. This requirement is intended to protect the patient and ensure that translations of patient materials are of the highest quality. Other review boards (including pharmaceutical) and regulatory processes require back translations to verify advertising and promotional claims, and the content suitability of documentation.

Back translation should be a part of the process if the translation is especially complex. High-value information must be completely accurate regardless of the target language and reverse translation is a way to ensure that. Back translation helps meet legal requirements and is considered an effective quality assurance and risk management tool.

Subject areas in which back translation is common or advisable:

  • pharmaceutical industry
  • medical devices and scientific equipment
  • clinical trials and research
  • medical/consent forms
  • surveys/questionnaires
  • export packaging
  • food products labelling
  • contracts and legal instruments
  • financial reports
  • operating instruction manuals
  • marketing slogans and collateral

Benefits of reverse translation for you, the client

Using the reverse translation method, clients who are not fluent in every target language they require can assess the quality of the translation. In specific situations, you may also be able to evaluate the effectiveness of your original text for the reader.

A “second opinion” from another translator can help you better understand the initial translation and quickly identify differences between it and source text. This enables you to compare the two texts without having to spend too much time on it. Reverse translation can also be used to evaluate the performance of your LSP.

Keep in mind that discrepancies between the initial and back translation may indicate of potential issues with the translation (such as problematic style choices), or individual preferences and style, which are not incorrect. It would be unfair to use the comparison report alone decide on the quality of an LSP. Instead, this feedback should be sent to the translator for review, so they can make any adjustments to their work or provide you with further explanations of their stylistic and terminological choices.

It is essential to work with the same initial translator of the original source text to rework the translation based on the back translation feedback. It is a waste of time and money to use a new linguist without prior knowledge of this project. With back translation to control for accuracy, you are able to take control of your quality assurance process. In terms of paperwork and risk management, it is an extremely transparent method.

However, if not done correctly, reverse translation may reduce the overall quality of the translation. To achieve the best results, it is advisable to use a professional linguist proficient in both (source and target) languages.

A back translation will not:

  1. evaluate the quality of expression. Most translations need to be more than accurate – they need to be worded well and read naturally. A style review does this.
  2. identify typos, grammar, spelling, or punctuation errors. A proofreader does this.
  3. identify ambiguities, i.e. parts of the original text that can be interpreted in more than one way, potentially leading readers to confusion or, worse, misunderstanding.

Fortunately, quality-conscious LSPs routinely do style reviews, use proofreaders, and ask translators to check for ambiguities in the source text.

Advantages and disadvantages of back translation


  • A proven method for confirming translation accuracy
  • Improves quality control
  • Good risk management tool
  • More transparent than other quality assurance methods
  • Provides clear proof and documentation


  • Cannot be used to evaluate other translation quality criteria
  • Costly
  • Time-consuming
  • Done improperly, it can compromise rather than improve the quality of the translation

What errors or pitfalls have you avoided through back translation and consequent review? Are there any other types of translation or localisation projects that benefit from reverse translation? Do share your thoughts and experiences in the comments section below.

At Alamma, we are happy to discuss how our experienced translators can use this procedure as an additional quality assurance. For more information or an answer to any questions you may have, feel free to contact us at