WASHINGTON - Thanksgiving online sales in the United States are expected to reach a record $3.5 billion, up about 20 percent from last year, according to newest data from Adobe, which tracks and analyzes online sales.

Adobe also forecasted retail e-commerce and mobile commerce totals of $5.9 billion on Black Friday, the day following Thanksgiving Day, and $7.8 billion on Cyber Monday, the Monday following the Thanksgiving holiday.

Figures from Internet Retailer, a publisher of e-commerce news and analysis, predicted that the total amount to be spent over the period between Thanksgiving Day and Cyber Monday will reach $21.6 billion, a quarter more than what Adobe estimated.

For the whole holiday season, which started in late November and will last for about a month, online sales could hit a record $124 billion, up by 15 percent from last year, said Adobe, which tracks 80 percent of online transactions at 100 of the largest retailers in the United States.

According to an annual survey, US consumers will spend an average of 1,007 dollars during holiday season this year, up 4.1 percent from last year, the National Retail Federation said last month.

Overall, e-commerce continues to account for between 10 and 20 percent of all retail sales, largely the same proportion as in the past few years, tech website TechCrunch reported.

For online sales, some 48 percent of visits to retailers come from smartphones, compared with 43 percent of visits from desktop, Adobe said. However, 63 percent of sales still happen on desktops and laptops, compared with 28 percent of sales on smartphones.