In a comparison of accommodation costs, Comparis, the Swiss consumer information agency, found that an average three to 3½-room apartment in Zurich rents for 2,432 francs a month.
This compares with 1,111 francs in watch-making town La Chaux-de-Fonds.
Apartments in Geneva are the second priciest at 2,029 francs.
But flats in Geneva are also the smallest on average in the country at 61 square metres for a 3½-room pad.
This compares with an average off 77 square metres across Switzerland and 82 square metres in Zurich, where apartments are rated the biggest in the country.
On a cost per square metre basis, apartments in Geneva are the most expensive at more than 33 francs, compared to 30 francs in Zurich.
In La Chaux-de-Fonds the cost per square metre is 14 francs.
Comparis based its figures on 35,000 housing adverts published on its website between January 2013 and March 31st 2015.
The rents do not include charges that are typically added to cover management and administrative costs.