UPS predicts that tomorrow (20 December) will be its busiest day of the year with an estimated 28 million packages delivered worldwide.

The parcels giant expects to deliver over 12 million more packages on its busiest day than its daily worldwide average of 15.8 million parcels.

It anticipates delivering 527 million parcels globally in the four weeks running up to Christmas, a 9.7% increase on 2011’s 480 million.

The carrier also expects a surge in return volumes on 3 January, when it predicts that 520,000 parcels will  be sent back to retailers in a single day - it expects to handle more than 2 million returns in the first week of the new year.

UPS retail marketing director David Sisco said: “We’ve seen a 15% increase in retail returns over the last year. UPS research shows that 63% of online shoppers review a retailer’s returns policy before making a purchase.”

UPS completes its London 2012 contract this month.