Many travellers consider moving abroad at some point – there are 222 million expats across the world, after all – but the grass isn't always greener.

This week, consultancy firm Mercer released an index of the world's most expensive cities for expats. Find out where topped the list below.

10. Beijing, China

It might surprise you that Beijing ranks one of the most expensive cities to live in, as it's known as a reasonably affordable destination for travellers. Get the Rough Guide to China before you go for the best budget travel tips.

Forbidden City, Beijing, ChinaPixabay / CC0

9. N'Djamena, Chad

While living like a local in Chad can be cheap, expats can often shell out as much as $12 for a hamburger.

Chad, AfricaImage by Ismouz on Flickr (CC BY 2.0)

8. Geneva, Switzerland

Switzerland isn't easy on the pocket for travellers and expats alike. Budget breaks can be had if you're so inclined; our Rough Guide to Europe on a Budget has plenty of advice.

Geneva, Switzerland, EuropePixabay / CC0

7. Shanghai, China

As one of the world's fastest-growing cities, Shanghai is home to some of the most extravagant hotels, restaurants and shops around the globe. Get beyond the glitz and discover the locals' city with the Rough Guide to Shanghai.

Shanghai, ChinaPixabay / CC0

6. Kinshasa, Democratic Republic of Congo

Expecting Kinshasa to be affordable? Think again. Apartment rental here can apparently cost up to US$8000 a month, and a gallon of milk can set you back up to US$10.

2128154682_0681299a77_bImage by Irene2005 on Flickr (CC BY 2.0)

5. Tokyo, Japan

All eyes are on Tokyo as the city prepares to host the 2020 Olympic Games. But if you want to live here, you might want to reconsider. Thankfully, we've got plenty of tips for getting the most of your money in our Rough Guide to Japan.

Tokyo, JapanPixabayCC0

4. Singapore

Singapore came seventh in a ranking of the world's most expensive tourist destinations earlier this year, and it doesn't look much rosier for expats either. Check out the Rough Guide to Southeast Asia on a Budget for our favourite affordable spots in the city.

Marina bay, Singapore, AsiaPixabayCC0

3. Zurich, Switzerland

A second entry for Switzerland confirms the country is one of the most expensive places to live and travel in Europe.

Zurich, Switzerland PixabayCC0

2. Luanda, Angola

Having moved down from the top spot this year, Luanda remains of the most expensive places for expats.

Luanda, Angola, AfricaImage by David Stanley on Flickr (CC BY 2.0)

1. Hong Kong

Hong Kong has been named the world's most expensive expat city in 2016. A cup of coffee here can set you back US$7.80, so make sure you know where to go before your trip.

Temple garden in Hong Kong, ChinaPixabayCC0

Compare flights, find toursbook hostels and hotels for your trip, and don’t forget to buy travel insurance before you go. Featured image Pixabay/CC0