Retail research firm Verdict projects online spending will increase to £67bn by 2020, from £21bn in 2009, while purchases made on the highstreet will fall to £247bn from £265bn over the same period.
The study predicts the internet will account for in every five pounds of British retail spending by 2020 when purchases of electrical goods and books made online will overtake those made in physical stores for the first time.
Verdict forecasts that online spending on electrical goods will hit £10bn by 2020, overtaking purchases made in bricks and mortar stores, which will total about £9.2bn.
The research firm projects online purchases of clothing and footwear and health and beauty products are all set to quadruple over the same period.
The study was carried out by Verdict on behalf of eBay.