Template:Convert

({{ #expr: * {{ #switch: {{{2|}}} }} round {{#ifeq: {{{4|}}} | | | {{{4}}} }} }}}|m=metre{{!}}m|ft=foot (unit of length){{!}}|ft}}) {{esoteric}}
 * ft = {{#switch: {{{3|}}}|m=0.3048}}
 * m = {{#switch: {{{3|}}}|ft=3.2808399}}