This template uses Lua :
{{ Infobox dim }} is used inside infoboxes to determine the size of an object. This is passed to geohack to make appropriate map sizes. Parameters are all optional:
length_mi
length_km
width_mi
width_km
area_mi2
area_km2
area_acre
area_ha
{{ Infobox dim/core |{{ #if :{{{ length_mi |}}}|{{ #expr :{{{ length_mi }}} *1.609}}|{{{ length_km |}}} }}
|{{ #if :{{{ width_mi |}}}|{{ #expr :{{{ width_mi }}} *1.609}}|{{{ width_km |}}} }}
|{{ #switch : 1
| {{ #if :{{{ area_mi2 |}}}| 1| 0}} = {{ #expr :{{{ area_mi2 }}} *2.59}}
| {{ #if :{{{ area_acre |}}}| 1| 0}} = {{ #expr :{{{ area_acre }}} *0.004047}}
| {{ #if :{{{ area_ha |}}}| 1| 0}} = {{ #expr :{{{ area_ha }}} *0.01}}
| {{ #if :{{{ area_km2 |}}}| 1| 0}} = {{{ area_km2 }}} }} }}