The decision will prompt further speculation that the magazine, which has lost its spot as the bestselling women's glossy to Conde Nast's handbag-sized Glamour, will eventually move to a smaller size permanently.
Early results for the October issue of Cosmopolitan, produced in two sizes for WH Smith travel outlets and displayed side by side, indicate a sales increase of 40% over normal sales in those outlets, which account for about 10% of Cosmopolitan's total sales.
Research conducted among a Cosmopolitan reader panel showed that commuters and travellers preferred the smaller size. "There were clear indicators that people commuting into work or going on holiday wanted something more portable, and liked the travel-size," said Cosmopolitan publishing director Jan Adcock. "But some still prefer the bigger format for reading at home. We didn't get any negative feedback at all."
Encouraged by the results, Adcock is extending the trial to cover the December and January issues, with both sizes again available in the same travel outlets. The handbag-sized edition will retain its £2.50 cover price, a discount of 30p on the normal size.
Adcock said that no decision would be taken on whether to publish only in the smaller size until the results of the trials had been assessed.