Architects' Data also simply known as the Neufert, is a reference book for spatial requirements in building design and site planning. First published in 1936 by Ernst Neufert, its 39 German editions and translations into 17 languages have sold over 500,000 copies. The first English version was published in 1970 and was translated from the original German by Rudolf Herz.

The book is conceived to help the initial design of buildings by providing extensive information about spatial requirements. Dealing mostly with ergonomics and with functional building layouts, thousands of drawings illustrate the text, organised according to building typologies. Weighting now slightly less than two kilograms, it has been continuously updated.