These are lists of the world's most expensive cities for expatriate employees (not residents), according to the Mercer, ECA International and Xpatulator.com  cost-of-living surveys. Other surveys from online collaborative indices, such as Numbeo, Expatistan, or Eardex are not covered by this article.
Various factors enter into a city's cost-of-living for expatriate employees, such as monetary value, consumer confidence, investment, interest rates, exchange rates of the country's currency, and housing costs. This list does not account for cost-of-living savings accrued to local citizens through government-subsidized housing, health care, and education, differences in taxation, and many other factors irrelevant to expatriates. Cost of living may be much higher for expatriates than for local residents in a developing country, especially if expatriates expect a standard of living similar to a developed country.
ECAwas invoked but never defined (see the help page).