I'm translating a wordpress site and need more clarity around these terms. Can anyone please lend a hand with some definitions and differences between .po .mo and .pot files with wordpress localization?

1 Answer 1


These are not any kind of WP's own format but rather just gettext file types which WP implements.

Translate Handbook has following definitions in its Glossary:

MO files: MO, or Machine Object is a binary data file that contains object data referenced by a program. It is typically used to translate program code, and may be loaded or imported into the GNU gettext program.

PO files: PO files are the files which contain the actual translations. Each language will have its own PO file, for example, for French there would be a fr.po file, for german there would be a de.po, for American English there might be en-US.po.

POT file: POT files are the template files for PO files. They will have all the translation strings left empty. A POT file is essentially an empty PO file without the translations, with just the original strings.

The technical details of file formats can be found in gettext documentation:

  • So, to understand it better, in a nutshell mo and pot files are left intact (mo file is essentially made automatically by using a program, for example poedit)? I still dont understand when we need a pot file.. Commented Feb 27, 2018 at 0:41
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    POT file is used whenever someone starts a new PO file for translation to a new language. So the workflow is POT (original strings) to PO (original strings and their translation to a specific language) to MO (compiled binary result).
    – Rarst
    Commented Feb 27, 2018 at 6:42
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    I would advise to just ask a new question. :) You are dragging your very specific problem (customization not working) into a very general questions (what are the file formats).
    – Rarst
    Commented Feb 27, 2018 at 13:11
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    @Er.AmitJoshi I have added links to technical details, if you are curious about internals. :)
    – Rarst
    Commented Dec 11, 2018 at 8:19
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    @landed yes, mo files are binary format, they are not supposed to be human-readable.
    – Rarst
    Commented Nov 19, 2019 at 11:23

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