Purpose – The purpose of this paper is to study the minimum necessary net internal area of dwellings that should be established by Portuguese building regulations. Design/methodology/approach – The following tasks are carried out: selecting the furniture and equipment necessary for each dwelling; determining the size of furniture and equipment and its typical arrangement; conceiving models of functional spaces; determining the net area of functional spaces and dwellings; comparing results with statistics on housing construction in Portugal and with mandatory area standards used in Portugal and ten other European countries. Findings – The paper finds that the net internal area presently set by Portuguese building regulations should be increased by 5 to 15 percent. The net internal area figure obtained by the study is similar to mandatory regulations established by some other European countries. Research limitations/implications – The study focuses on the net internal area of dwellings, although other space standards are also important to assuring the practicability of dwelling spaces; area standards were set on the basis of the current Portuguese situation and required adaptation when used in different social, cultural and economic contexts; area standards constitute a safety-net against unacceptable dwellings rather than good practice guidelines. Practical implications – The results may be used to support a review of Portuguese building regulations and provide guidelines for the design of dwellings. Originality/value – A methodology to determine area standards is presented and applied. Up-to-date information on furniture size and arrangements is collected. The comparison enables an understanding of how the results compare in a European context.Housing Quality and Process InnovationOTB Research Institut