Overall Boxing Day activity levels are down 10.6% across all UK retail destinations, as at 10:00, compared to 26 December last year.
Analysts have told BBC News that bricks-and-mortar stores are becoming less profitable as they are expensive to keep open due to rising energy costs and, for some, Bank Holiday overtime pay for staff.
Online shops are cheaper to operate and generally have fewer overheads.
MRI Software’s Jenni Matthews said a year-on-year rise in footfall is anticipated from 27 December.
She said that, despite the early data, it was expected that many shoppers would “emerge from their post-Christmas slumber looking to replenish their groceries and see what Boxing Day bargains are available”.
The company will release more footfall data later.