Template:Birth based on age as of date/doc

This is a documentation subpage for Template:Birth based on age as of date.
It may contain usage information, categories and other content that is not part of the original template page.

This template is used on approximately 5,900 pages and changes may be widely noticed. Test changes in the template's /sandbox or /testcases subpages, or in your own user subpage. Consider discussing changes on the talk page before implementing them.

Preview message: Transclusion count updated automatically (see documentation).

This template employs intricate features of template syntax.

You are encouraged to familiarise yourself with its setup and parser functions before editing the template. If your edit causes unexpected problems, please undo it quickly, as this template may appear on a large number of pages.
You can conduct experiments, and should test all major changes, in either , the general template sandbox, or your user space before changing anything here.

For a person whose date of birth is unknown, this template estimates the person's birth year and current age based on a given age at a certain date. This is useful when a reliable source states only their age at the time of publication.

If you have reason to believe the subject's age has been discussed by sources at more than one point in time, consider not using this template which, by definition, introduces a whole year's worth of error margin. For example, if a reliable source on May 1st, 2010 states Mr X is 29 years old and a different source on August 1st, 2020 states Mr X is 40 years old, then you can establish that Mr X was born no earlier than May 2nd, 1980. Using this template would in both instances suggest a birth year of 1979 or 1980. Since you know the former to be incorrect, using this template would be inappropriate.

If the subject has died, please use {{Birth based on age at death}} instead of this template. While as of 2024^[update] that template is just a wrapper of this one, this leaves open the possibility to use that template to recategorize the subject. Also, it makes sure you don't forget to suppress the age field.