Sharp shifts in exchange rates in recent months have altered the relative cost of living in cities around the world. The Economist Intelligence Unit's ranking (above), is based on price data collected in September 2008, then adjusted for recent exchange-rate movements. It shows Tokyo as the world's most expensive city, with a score of 152, closely followed by Osaka Kobe. The cheapest city is Karachi in Pakistan, with a score of 37.

This result contrasts with the ranking of September 2008 (below), which showed Oslo as the world's most expensive city, followed by several other European cities and two in Japan: Tokyo (at sixth place) and Osaka Kobe (at eighth, shared with London).

The disparity in the rankings makes it possible to see which cities have been relative winners or losers as a result of the currency dislocation. The main changes in the ranking occur among the most expensive cities. The decline of European currencies, most notably the euro, pound and the Norwegian krone, has driven a significant weakening in the relative cost of living for many European cities. Conversely, a stronger yen now means that the Japanese cities of Tokyo and Osaka have become the most expensive cities in the survey.

The Worldwide Cost of Living survey compares the cost of living in 140 cities worldwide. In each city field researchers gather and return a range of prices for over 160 items, from a loaf of bread to a luxury car. A cost-of-living index is calculated from the weighted average price data to express the difference between any two cities. The data quoted here uses New York as a base index of 100 for comparisons.