What the Mercer Cost of Living Index Measures
The Mercer Cost of Living Index compares the relative affordability of cities for internationally mobile employees. It is one of the most widely cited tools for expatriate compensation planning. Unlike consumer price indices that track a single country, Mercer isolates costs faced by a globally mobile worker living in a foreign city, benchmarked against a reference city (New York City) assigned a baseline index value of 100. The index helps employers design hardship allowances and relocation packages, and it gives assignees a realistic picture of purchasing power abroad.
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Mercer collects data across six broad categories: accommodation, transport, food, household goods, entertainment, and utilities. Each category is weighted based on typical expatriate spending patterns. The survey draws price data from local suppliers, retailers, and service providers in over 200 cities worldwide. Because it is run by a human resources consulting firm rather than a government statistical agency, the methodology is proprietary but consistently applied, making year-over-year comparisons possible.
How the Ranking Methodology Works
Mercer updates the Cost of Living Index annually, typically releasing results in the middle of the year for the upcoming assignment cycle. Data collectors visit or survey cities during a specified data-collection period, usually several months before publication. Prices are gathered for a standardized basket of goods and services, including a specific model of car, a defined menu of grocery items, rent for a furnished apartment in a particular neighborhood, and utility costs.
The methodology has several nuances worth noting. Exchange rates are converted at a fixed point in time, which means currency fluctuations can shift city rankings even if local prices do not change. Housing costs are a major driver of the overall index because they represent the single largest expense for most expatriates. Cities where employers must compete for a limited pool of housing, such as Hong Kong or Zurich, tend to rank at the top of the list.
2024 Findings and Notable Shifts
The most recent Mercer Cost of Living Index placed several East Asian and European cities at the top of the rankings, with Hong Kong, Singapore, and Zurich consistently appearing among the most expensive assignments. Cities in the Middle East, including Tel Aviv and Abu Dhabi, have also moved up in recent years, driven by strong demand for housing and imported goods. In some cases, weakening local currencies against the US dollar made destinations in Africa and parts of Eastern Europe relatively cheaper for assignees paid in a hard currency.
Year-over-year changes often reflect a combination of factors: inflation in local consumer prices, shifts in hotel and rental availability after pandemic-era mobility patterns, and geopolitical events that disrupt supply chains. Mercer highlights that the index captures relative cost, not absolute poverty, so a city can rank as expensive while offering a lower standard of living than a cheaper alternative.
Using the Index for Relocation Decisions
Employers use the Mercer Cost of Living Index to calculate hardship differentials and to set assignment budgets. An employee moving from New York to a city ranked at 150, for example, faces costs 50 percent higher than the baseline, which may be partially offset by a cost-of-living adjustment in their salary. The index also helps assignees compare destinations: a city ranked 80 is objectively cheaper than one ranked 120, all else being equal.
For individuals planning a move without employer support, the index provides a starting point for estimating expenses, but it should be paired with local salary data and personal lifestyle preferences. Renting in a city center versus a suburb, choosing local schools over international ones, and adjusting travel frequency all affect real-world costs in ways a single index number cannot capture.
Limitations and Complementary Data Sources
The Mercer Cost of Living Index has known limitations. It reflects the experience of a relatively affluent expatriate, not a local resident with a local income. Goods and services are priced for quality and availability in international supermarkets and hotels, which may not represent how ordinary households shop. The basket does not include income taxes, which can vary dramatically between countries and significantly affect net disposable income.
Organizations and individuals seeking a fuller picture often cross-reference Mercer with other resources. The Economist Intelligence Unit publishes a Worldwide Cost of Living survey using a similar methodology. Numbeo aggregates crowd-sourced local prices and offers a living-cost calculator. Government statistics agencies in major economies publish consumer price indices that track inflation for domestic residents. Using Mercer alongside these sources provides both a global ranking and a grounded local perspective.
Planning Ahead with Mercer Data
Because the Mercer Cost of Living Index is released annually with a lag, planning for a future assignment requires using the most recent available survey while monitoring exchange-rate trends and local market conditions. Employers with large global workforces often maintain internal cost models that layer Mercer rankings on top of real-time rent indices and inflation forecasts. Assignees who understand both the index and its gaps are better positioned to negotiate packages, save effectively, and manage expectations before arriving in a new city.
The index remains a cornerstone of international mobility management, valued for its consistency and breadth. Whether the goal is to compare a short-term posting in London with a long-term move to São Paulo, Mercer provides a common language for talking about cost across borders.