How to tell if a travel location is "affordable"?

The Economist Magazine invented the so-called "Big Mac Index" as an attempt to measure the relative purchasing power between various currencies.

THE Big Mac index was invented by The Economist in 1986 as a lighthearted guide to whether currencies are at their “correct” level. It is based on the theory of purchasing-power parity (PPP), the notion that in the long run exchange rates should move towards the rate that would equalise the prices of an identical basket of goods and services (in this case, a burger) in any two countries. For example, the average price of a Big Mac in America in January 2016 was $4.93; in China it was only $2.68 at market exchange rates. So the "raw" Big Mac index says that the yuan was undervalued by 46% at that time.

Source: Big Mac Index

For the case you mentioned, the UK vs Korea, the indices against the dollar are...

...which suggests that at the moment, the UK gives a bigger 'bang for your buck' because the index is undervalued more. But remember the caveat offered by the "Economist"...

Burgernomics was never intended as a precise gauge of currency misalignment, merely a tool to make exchange-rate theory more digestible.

Although Numbeo, a crowdsourced city comparison tool, is for cost of living and not travelling it is still an extremely useful resource even for short stays. For example Vancouver vs Jerusalem shows prices in restaurants, markets, rent per month (while you likely won't rent for a month the ratio between two cities will be similar for a daily rent).

The problem with many of the online comparison tools is that they don't necessarily reflect the kind of travel lifestyle you're going after. Here's what I normally do to get a good estimate:

1. Go to HostelWorld, find the highest rated hostel and check their daily rate for a 4-person room. In Prague that's around 30EUR, while in London it's closer to 50EUR.

2. Go on Numbeo and check out the local restaurant prices, in the Meal, Inexpensive Restaurant section.

3. Go on Uber and check out their rates for the city (or that country's capital). If the taxi is cheap enough I'll often completely skip on public transport.

4. If the taxi is too expensive or Uber is unavailable, go on Numbeo again to find the price of a single public transport ticket.

5. Go on Foursquare and check out the entry fee for the top rated museum. Surprisingly London is actually cheap in this regard, as most museums are free or almost free.

Since I don't spend much money outside these categories when I travel, this gives me a great idea of exactly how much I will end up spending.

Numbeo is accurate for the cities I tried, but in many areas there are very cheap long term basic accommodation and only luxury travel accommodation for tourists.

I think that someone who asks this question has a finite budget, the option to go where he wants and desires to get the most "bangs for his bucks". Most of the answers I saw were for luxury business trip to a fixed location.

Also cost of traveling is relative to the way you travel, what you do, and for how long. I think it is best to separate things into various expense items.

• Cost of travel

Yes, the money for the plane ticket may already be spent, but the length of the trip gives you a daily budget. A $1000 ticket for a 2 weeks trip is not accounted the same way as a ticket for a 2 month trip. This impacts your total spending and has to be integrated into the trip as a daily expense. This can lead to going to a more expensive country that has a cheaper travel cost.

• Hotel

There are some good sites for hotels but many of the hotels listed pay to be there and are desperate for customers because they are badly located and not- competitively priced. The main problem however is that they only tend to list hotels with 2-3 stars and above. In Europe that is fine but in most countries I travel to, budget hotels don’t want to pass the burden and expense of being rated by stars giving agencies. So, the bottom range in hotel sites are middle range in many countries and many under $50 hotels with great values just do not exist on the internet.

• Food

This cost greatly varies; sites like Numbeo are good for that. Meal budgeting is very personal and is one of the great variation. To save money there are usually many cheap street foods and supermarkets.

• Transport

Either cost of inner-city transport or averaged daily inter-city transport.

• Social and drinking

One of the greatest relatives, from near zero to spending most of the budget in discos and pub crawling.

• Miscellaneous, Groceries, Fees

Variable, in some countries miscellaneous costs can be greater than hotel and food. Museum and sites fees can be a separate category if they are major daily expenses.

So, to answer the question you need to do some estimates based on several sites on the different components of the budget.

So these vary, while some people put over 60% of their budgets in hotel, for me I like cheap hotels but nice food, and a social life. So for me I would estimate based on 100 that travel=10, hotel=30, Food=25, transport=5, Social=20, Misc=10.

So, determine your budget priorities and get estimates on these areas.

Cost of living indexes don't fully apply to tourism as residents incur a different set of costs to visitors. Also, per-diems are used to provide an estimation of how much a business traveller might be expected to spend and be allowed to claim back from their employer. A business traveller is unlikely to be able to claim for the cost of renting a beach chair or a visit to a theme park.

A bit of research finds the term: "Tourism Price Competitiveness" and an index can be seen here for 2015: The Travel & Tourism Competitiveness Index Ranking 2015. The index is formed from many things that are related to the country's infrastructure, business costs, health costs, education costs (as they influence cost of the labour market), up to costs of hotels, airline tickets and fuel and others that inevitably influence the final price of your big mac.

From The Travel & Tourism Competitiveness Report 2009

Determinants of tourism price competitiveness

Tourism price competitiveness is essentially a matter of the prices of the goods and services that tourists buy, expressed in some common currency

Given the relative index of the UK at 5.12 and South Korea at 4.37, the cost of a big mac in the UK at $4.22 divided by 5.12 and multiplied by 4.37 = $3.60. Very very close to @GayotFow's price. :)