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.
The Economist Intelligence Unit's Worldwide Cost of Living ranking is based on price data that are adjusted for recent exchange-rate movements. The price of housing, generally the largest cost of living, is not included as this tends to be provided by the company and does not factor in adjusting the salary of the expatriate employee.
Mercer's Cost of Living surveys are taken in March of each year.
The survey covers 214 cities around the world and measures the comparative cost of over 200 items in each location, including housing, transport, food, clothing, household goods and entertainment. It is designed to help multinational companies and governments determine compensation allowances for their expatriate employees. New York is used as the base city and all other cities are compared against New York. The cost of housing plays an important part in determining where cities are ranked.
Two main factors determine a city’s ranking in Mercer’s survey - the relative strength of the relevant currency against the US dollar over the prior 12 months and price movements over the prior 12 months compared to those in New York City as the base.
Every March and September, ECA International calculates the cost of living for expatriates in almost 400 cities. The survey does not include certain living costs such as accommodation, utilities (electricity, gas, water costs), car purchase and school fees. These are usually compensated for separately in expatriate packages from cost of living allowances.