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{{Documentation subpage}}

{{High-use}}
{{Template redirect|Bbad|Birth year from age as of date|Birth year from age at date}}
{{Lua|Module:Birth based on age as of dates}}

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 [[wp:reliable source|reliable source]] states only their age at the time of publication.

{{Notice|This template can be used whether '''only one''' or '''multiple''' points in time are available.}}

{{Notice|This template is intended for living people.}}

If the subject has died, please use {{tl|Birth based on age at death}} instead of this template. While {{asof|2024|lc=y}} 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.

== Syntax ==
=== Typical use ===
<syntaxhighlight lang="wikitext"> {{birth based on age as of date | age | year | month | day }} </syntaxhighlight>
<div style="margin-left:1.6em;">Code:</div>
<div style="margin-left:3.2em;"><code><nowiki>{{birth based on age as of date|50|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}<nowiki>}}</nowiki></code></div>
<div style="margin-left:1.6em;">Result:</div>
<div style="margin-left:3.2em;">{{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}}}
</div>
The age, year, and day must be supplied as [[natural number]]s; month can be specified as a natural number as well as by name or abbreviation (e.g. "August" or "Aug"). The [[Gregorian calendar]] is assumed, with no special support provided for [[dual dating]] or the difference between [[Old Style and New Style dates]].

If only the publication year for a source is known, the "day" and "month" fields can be omitted.

=== No age ===
In some contexts—like the lead sentence of a biography—it may be desirable to show only the birth year, and not a person’s age. To suppress the age field, set {{para|noage|<var>any value</var>}}:

<div style="margin-left:1.6em;">Code:</div>
<div style="margin-left:3.2em;"><code><nowiki>{{birth based on age as of date|50|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|noage=yes<nowiki>}}</nowiki></code></div>
<div style="margin-left:3.2em;"><code><nowiki>{{birth based on age as of date|50|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|noage=1<nowiki>}}</nowiki></code></div>

<div style="margin-left:1.6em;">Result:</div>
<div style="margin-left:3.2em;">{{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|noage=yes}}</div>
<div style="margin-left:3.2em;">{{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|noage=1}}</div>

; Note
: The parameter {{Para|noage}} was {{Diff2|538967200|added April 2013}} and initially only accepted a value of <code>1</code>, such as {{Para|noage|1}}. It was {{Diff2|907862722|updated July 2019}} to accept any value, such as {{Para|noage|yes}}.

=== Slash separator ===
In general, the two possible birth years should be written out as: {{xt|1950 or 1951}}. In contexts which are tight for space, the separator between the two possible years should be a slash: {{xt|1950/1951}}.

To use the <code>/</code> separator, add {{para|slash|<var>any value</var>}}.

<div style="margin-left:1.6em;">Code:</div>
<div style="margin-left:3.2em;"><code><nowiki>{{birth based on age as of date|50|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|slash=yes<nowiki>}}</nowiki></code></div>
<div style="margin-left:3.2em;"><code><nowiki>{{birth based on age as of date|50|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|slash=1<nowiki>}}</nowiki></code></div>

<div style="margin-left:1.6em;">Result:</div>
<div style="margin-left:3.2em;">{{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|slash=yes}}</div>
<div style="margin-left:3.2em;">{{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|slash=1}}</div>

; Note
: The parameter {{Para|slash}} was {{Diff2|1152429370|added April 2023}} when the template was updated to separate years with <code> or</code> instead of <code>/</code>. It replaced the now deprecated parameter {{Para|mos}}, which was {{Diff2|692544429|added November 2015}} and {{Diff2|1166652940|removed July 2023}}.

=== Multiple dates ===
<syntaxhighlight lang="wikitext"> {{birth based on age as of date | age | year | month | day | age | year | month | day }} </syntaxhighlight>
<div style="margin-left:1.6em;">Code:</div>
<div style="margin-left:3.2em;"><code><nowiki>{{birth based on age as of date|50|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}<nowiki>|51|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|12|31<nowiki>}}</nowiki></code></div>
<div style="margin-left:1.6em;">Result:</div>
<div style="margin-left:3.2em;">{{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|51|{{#expr:{{CURRENTYEAR}}-2}}|12|31}}
</div>
Two or more dates can be entered, using the same format as for a single date. In this case, the "day" and "month" fields cannot be omitted.

== Examples ==
If, for example, a reference dated July 4, {{#expr:{{CURRENTYEAR}}-2}} mentions that someone is 50 years old, that person's birth year and age can be rendered using:
<div style="margin-left:1.6em;"><code><nowiki>{{birth based on age as of date|50|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|July|4}}</code></div>

{| class="plainlinksneverexpand" style="margin-top:0;"
!style="border:1px solid #aaa;background:#dfd;"|
The following examples are for a person reported as being 50 years old in {{#expr:{{CURRENTYEAR}}-1}}
|-
|
{{Aligned table
|class=wikitable |colstyle=padding-right:1.0em;
|col1style=font-family:monospace;padding-right:1.0em;
|row1header=on| {{sans-serif|Template code}} | Result

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTH}}|{{CURRENTDAY}}}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTH}}|{{CURRENTDAY}}}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTHNAME}}|{{CURRENTDAY}}}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTHNAME}}|{{CURRENTDAY}}}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31|slash{{=}}yes}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31|slash=yes}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1|slash{{=}}1}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1|slash=1}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31|noage{{=}}yes}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31|noage=yes}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1|noage{{=}}1}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1|noage=1}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31|noage{{=}}yes|slash{{=}}yes}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31|noage=yes|slash=yes}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1|noage{{=}}1|slash{{=}}1}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1|noage=1|slash=1}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTHNAME}}}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTHNAME}}}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}}}

| {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|51|{{#expr:{{CURRENTYEAR}}-2}}|12|31}}
| {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|51|{{#expr:{{CURRENTYEAR}}-2}}|12|31}}
}}
|}

== TemplateData ==
{{TemplateDataHeader}}
<templatedata>
{
"params": {
"1": {
"label": "Age",
"description": "Age of subject at date of reference's publication.",
"example": "55",
"type": "number",
"required": true
},
"2": {
"label": "Year",
"description": "Year of publication of reference.",
"example": "1950",
"type": "number",
"required": true
},
"3": {
"label": "Month",
"description": "Month of publication of reference.",
"example": "8 or August",
"type": "string",
"suggested": true
},
"4": {
"label": "Day",
"description": "Day of publication of reference.",
"example": "21",
"type": "number",
"suggested": true
},
"noage": {
"label": "Hide age",
"description": "Set to any value to display birth years without the ages. If this parameter is omitted or contains no value, the age is displayed.",
"type": "boolean",
"required": false,
"suggestedvalues": [
"yes", "y", "1"
]
},
"slash": {
"label": "Slash separator",
"description": "Set to any value to separate birth years with a '/' for tight spaces (e.g., table cells). If this parameter is omitted or contains no value, birth years are separated with ' or '.",
"type": "boolean",
"required": false,
"suggestedvalues": [
"yes", "y", "1"
]
}
},
"description": "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.",
"format": "inline",
"paramOrder": [
"1",
"2",
"3",
"4",
"noage",
"slash"
]
}
</templatedata>

==Tracking category==
* {{Category link with count|Pages using birth based on age as of date with unknown parameters}}

==See also==
* {{tl|Birth based on age at death}}, a [[Wikipedia:Wrapper templates|wrapper template]] implemented using {{tl|Birth based on age as of date}} with {{para|noage|1}}
* {{tl|Birth date and age}}, when exact date of birth is known

{{Birth, death and age templates |BDA}}

<includeonly>{{sandbox other||

[[Category:Date mathematics templates]]
[[Category:Templates that add a tracking category]]

}}</includeonly>

Template:Birth based on age as of date/doc - Revision history

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wiki>Chaotic Enby: fix layout