Here I thought a kilogram was defined by water... oh well, looks like that definition is slightly outdated.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Litre#Rough_conversions" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Litre#Rough_conversions</a>