Online shoppers who habitually take advantage of free returns by over-ordering are placing increasing pressure on UK retailers, according to a survey.
The emergence of "serial returners" - those who have no intention of keeping every item - is negatively affecting six in 10 retailers (57%), and one in five (20%) have increased their prices to cover the cost, the study by Barclaycard found.
An estimated 30% of shoppers deliberately over-buy and subsequently return unwanted items, the survey found.
Almost six in 10 (58%) say a retailer's returns policy influences their decision to buy, and almost half (47%) of these would not order an item if they had to pay to send it back.
But almost half of shoppers say that standardising clothing and shoe sizes would save them from having to order multiple items to ensure a correct fit.
And 18% said a better in-store experience, such as shortened queues for fitting rooms, would reduce the number of returns they make.
The findings come as spending across digital channels rose 14.1% in 2015 compared with just 1.1% in stores.
Sharon Manikon, director of customer solutions at Barclaycard Global Payment Acceptance, said: "Today's time-pressed shopper expects the process to be fast, easy and free - and that applies to both buying goods as well as returning them.
"Online spending will continue to rise and the need to keep pace with customer demands presents a dilemma for businesses needing to protect their bottom line.
"From developing universal sizing to offering virtual dressing rooms, the key for today's businesses is to determine which innovations work best for them while ensuring they don't lose out to their more savvy competition."
:: Opinium Research surveyed 308 UK businesses and 2,003 consumers online and 2,016 UK adults who have returned items between March 31 and April 12.