This study examines charter school funding equity in 18 cities using 2019-20 data, the most recent available. The study uses official school district and state budget documents to capture every dollar flowing to schools, including in-kind services. The study answers the following questions: (1) What is the difference in per-pupil revenue between traditional public schools (TPS) and charter schools in major US cities in the 2019-20 school year? (2) Do differences in student demographics explain any funding differences between TPS and charter schools? (3) Does the relationship between TPS and charter school funding vary across categories of school revenue? and (4) Which cities are driving the results? Findings reveal that: (1) Charter school students across 18 cities receive an average of 30 percent less funding per pupil than students in TPS in 17 of those cities; (2) About 65 percent of the underfunding of public charter schools in the cities can be attributed to lower enrollments of students with disabilities in the charter sector; and (3) Charter schools receive less local funding, state funding, federal funding, and nonpublic funding than TPS.