A luxury store in Tokyo, Japan. REUTERS/Thomas Peter TPX Upmarket property agent Savills has produced a ranking of the most expensive cities to live and work in.

The index measures the combined cost of residential and office rental per person per year across leading world cities to give an idea of how much a company to budget per employee in any given city.

For instance, staff in Johannesburg will cost a minimum of $20,000 ($16,445) per person to cover the cost of renting a desk there and enough pay for them to rent a flat locally.

Of course staff will likely earn more to cover food and other living expenses, but Savills index is a useful rule of thumb to compare cities.

While it is aimed at employers — giving them an idea of labour costs — the fact that it includes property prices means that it gives everyone a good idea of the relative cost of living in various cities.

Yolande Barnes, head of Savills world research, says in an emailed statement: "World cities can become a victim of their own success when rents rise to the point where affordability becomes an issue."

She continues:

"Rapid urbanisation demands supply elasticity — the test for the top Alpha cities is to supply new business quarters and residential neighbourhoods while capturing the characteristics that made the city attractive in the first place. Growth without social, economic, or environmental loss is perhaps one of the biggest challenges facing our world cities today."

The average total cost of office and housing accommodation per worker per year in the 20 cities measured is $56,855. Savills looked at a combination of established world cities and up-and-coming rivals, dubbed "upstarts" by Savills.

Check out the ranking of the most expensive cities below: