Each comparison's home size (square footage) defaults to total living area according to the Annual Earnings specified in the Two City Comparison. You may modify the Square Feet in the Housing field of the Options panel to match the actual current home size of the employee's Base City home.
The Two City Comparison of the Geographic Assessor uses these default settings: Base City of the United States Average, Annual Earnings of $50,000, and home size of 1,613 square feet. Prior to the April 2016 data release, 2,200 square feet (the National Expenditure Pattern) was used as the default for all Base locations. Recent refinements to Local Expenditure datasets allow each Base location to have an individualized benchmark housing size to better reflect local housing costs.
See Data Background FAQ #20 for more information.
Please note: To return to the default values for all assumptions, click the 
button at the top of the Options panel.
The Geographic Assessor databases report estimated rental costs for up to a maximum rental home size assigned to each international country. This limitation (e.g., 1,600 square feet in Japan) reflects a country's normal, maximum home size based upon available data and where we have found extrapolation via regression analyses unreliable (or data unavailable) for larger home sizes.
Please note that this home size maximum limit effectively equalizes cost of living for international comparisons, and lowers cost-of-living differentials overall between some international cities and North American cities. That is, if the program did not limit the home size for the international Destination City, the overall cost-of-living differential would be much greater. The higher the earnings level, the bigger this methodology's impact. For example, smaller home size results in more funds distributed to the "Miscellaneous" category, which is an equalizer.
See Two City Comparison - Background for more information.