We see a lot of questions about How much does it cost to spend X days in Y city? These questions always get closed, as there is such a range of lifestyles, and one could potentially stay in a 5-star hotel, and dine out every meal, or use CouchSurfing and eat ramen noodles, or anything in between.
So for this question, I'm not asking how much it will cost to stay in a particular city, but rather I'm interested in determining the relative cost of staying in a city -particularly food, lodging and public transportation costs.
In the US, comparing the GSA Per Diem rates can serve as a good indicator of what one might expect to spend. I rarely, if ever, spend as much as the GSA Per Diem rates would indicate, but by comparing the per diem rates between two cities, I can get a rough idea whether one city is more expensive than the other, for a short-term stay.
Is there any way to do something similar on an international scale?
A generic cost-of-living index would be a close approximation if there is no such thing as a cost-of-travel index, although the cost of living can be somewhat misleading, as it often includes things like automobiles, income taxes, and other expenses which may be disproportionately high (or low) compared to the costs associated with a short-term stay. Further, most cost-of-living resources appear to be either too localized (such as the Consumer Price Index which is only calculated in the US), or too broad, such as various cost of living per country calculators, making it difficult to compare between two cities.
So in summary:
Is there any defined way to compare the cost of short-term stays between various international cities?
As a second choice, is there any defined way to determine the cost of living between various international cities?