The most expensive are flights originating in Belgium where the average cost is US$54.63 per 100km.
New Zealand was 24th cheapest last year but climbs up the affordability ranking this year, placing 17th at US$8.43 per 100km as domestic and international competition intensifies.
Countries with small geographical domestic markets tend to be further down the list of affordability.
"Ticket prices fluctuate constantly and for many reasons. Some of the changes from one year to the next can be attributed to fuel prices, sociopolitical shifts like Brexit, and recent elections. Egypt and Turkey, for example, saw a decrease in ticket prices because of a decrease in demand as a result of regional turmoil," said Kiwi.com chief executive Oliver Dlouhý.
Britain has climbed up the affordability ranking from 32nd to 27th place.
In contrast travel within and from the United States slid from 17th place to 30th on the affordability front. Last year India was the cheapest place to fly, but is now in second place.
• Romania has the most affordable domestic flights on low cost airlines, at US$3.04 per 100 km of travel
• Qatar has the most expensive domestic flights on low cost airlines, at $87.50 per 100 km of travel
• Brazil has the most affordable domestic flights on full service airlines, at $3.98 per 100 km
• Chile has the most expensive domestic flights on full service airlines, at $152.01 per 100 km
• Sweden has the most affordable international flights on low cost airlines, at $1.31 per 100 km
• The United Arab Emirates has the most expensive international flight on low cost and full service airlines, at $38.81 and $49.13 per 100 km.
• Lithuania has the most affordable international flight on full service airlines, at $2.50 per 100 km.
Graphic / NZ Herald
To calculate the rankings, Kiwi.com analysed more than a million flights to find an average price of short-haul and long-haul flights on low cost and full service airlines from each of the countries.
Domestic flights were calculated by finding an average airfare from the country's capital to up to five major cities within the country, or to a major city nearby in a neighbouring country when no domestic flights were available.
The price of international travel was calculated based on flights from all international airports within the country, to several international hubs.
All flights were checked for the same dates of travel taking into account high and low seasons.
• The company was formerly known as Skypicker says Kiwi.com and says it is not named after the fruit, or the flightless bird, or the people of New Zealand, but ''instead it is a new meaning to a catchy word".
