For many, the notion of ‘measuring urban form’ will sound disturbing. Urban form is about visual images of cities, experiences, feelings, memories of place, thoughts and intellectual constructs anchored in the realm of the arts and the humanities. Anne Vernez Moudon however gives in the paper Urbanism by numbers (2009) a good argument to study the urban environment quantitatively as it offers urban designers the opportunity to practice their art with its due precision. Urban density is one of the measures that is used frequently in urban design practice, but is also questioned by many as it relates poorly to urban form (Alexander 1993, Forsyth 2003). The use of a concept with such a large “warning disclaimer” is disturbing. The Spacematrix method has contributed to a clarification of the existing Babel-like confusion in the terminology currently being used by urban planners working with urban density. The most important contribution of the Spacematrix method is, besides a clear definition of density, that density can be related to urban form and other performances and that urban form is thus measurable.