Nearly half of online sales fall through in the US, according to a report on the web’s biggest retail sites.

A study of eight of the web's most popular retail sites, by New York e-commerce consulting firm Creative Good, found 43 percent of all purchases failed because consumers either had trouble finding products, or problems occurred with the electronic checkout process that made completing the purchase too difficult.

The sites,,,, eToys,,, and, are some of the biggest hitters in web shopping in the US.

Problems with the electronic checkout accounted for 40 percent of all failed purchases. Although some shoppers managed to find a product and add it to their electronic shopping carts, many became frustrated by being asked for confusing account registration requirements, getting vague error messages that offered little or no help on how to proceed and an inability to order a specific quantity of items.

‘It was as if these customers made it to the cash register but the store would not let them pay,’ the study concludes.

"We believe that the Web is too hard to use," said Aamir Rehman, senior analyst at Creative Good and the principal author of the study. "The checkout process needs to make it clear to customers what they need to do and how to proceed to the next step."

Barrett Ladd, an analyst at US research firm Gomez Advisors, said the problems identified in the study shouldn't amount to a disaster for retailers, but warned online retailers are far from providing a top notch service.

"Some sites have started to focus on checkout, though few have done an exceptional job,” said Ladd. “Ideally, during the checkout process, firms should provide access to customer service information . . . especially privacy and security information.”