Freight transport and emissions are increasing rapidly and, until now, cities were not equipped to handle the associated challenges. Unlike passenger transport, urban planners and city leaders often lack comprehensive understanding, robust data and common terminologies, all of which have major implications for the management of urban freight transport systems. Many cities have recognized the importance of reducing greenhouse gas (GHG) emissions in the freight sector, however, they often lack reliable data to evaluate the freight transport performance and identify future priorities and directions. Calculating emissions is the first step. To this end, the EcoLogistics Self-monitoring Tool is developed collaboratively as a decision support system for local governments to estimate, evaluate and track their urban freight GHG emissions performance over time, as well as to engage in uniformed goal-setting and guide future actions in the most impactful way. The calculation methodology behind the tool is mainly based on the Global Protocol for Community-Scale GHG Emission Inventories: An Accounting and Reporting Standard for Cities (GPC) and the Global Logistics Emissions Council Framework for Logistics Emissions Accounting and Reporting (GLEC Framework).