A new analysis expects retail e-commerce sales worldwide to hit nearly $2 trillion this year and to more than double to $4 trillion by 2020.
The latest retail forecast from market research company eMarketer projected that e-commerce sales would grow at a 23.7 percent rate this year and account for 8.7 percent of overall global retail spending.
By 2020, e-commerce should comprise 14.6 percent of total retail sales.
"While the pace of growth for overall retail sales is subdued, the digital portion of sales continues to expand rapidly," the firm wrote.
The Asia-Pacific region's e-commerce market is expected to remain the world's largest throughout the period. This year, amid a projected 31.5 percent sales increase, the region will account for more than half of the global e-commerce.
As the region's middle class expands — along with internet access, e-commerce competition and logistics — e-commerce sales should reach $2.7 trillion over the subsequent five years.
North America will be the world's second-largest market this year at $423 billion and should see "consistent double-digit growth through 2020" as consumers broaden their online shopping habits.
Overall retail sales worldwide, which include e-commerce, conventional retail sales, the automotive sector and auction websites such as eBay, are expected to increase 6 percent this year to more than $22 trillion.
Although eMarketer projected slower future growth and lowered its forecast from its December report — a result of low oil prices and negative currency factors — total sales should climb to $27 trillion by 2020.