Walking is the most basic act of human which makes all equal and liberates them in the built environment. For defining how walking friendly the area is, walkability is an issue started to be discussed from its several different aspects. Although walkability is studied from several different disciplines, it has neither accurate definition nor definite criteria.Starting from 1990s, walkability has started to be measured with hard-copy walkability measurement tools (WMTs) and followed by web-based walkability measurement tools. In the literature, WMTs are generally used as a tool to measure the walkability level of the selected case. However, there are few studies which tries to understand and examine the background process of these WMTs.The aim of this thesis is to categorize and define the background idea of walkability measurement tools by criticizing their keystones and their main ideas. The mapping, clustering, tabling and analyzing processes are the main devices to develop critical analysis. In tabulation, two specific charts are composed: Comprehensive Data Chart and Content Analysis Chart. Under Comprehensive Data Chart, properties of WMT are defined and categorized. In Content Analysis Chart, each tool’s content of WMTs are compared and criticized. Finally, the thesis developed a critical analysis for defining, comparing and understanding each and every single WMT.