Australian consumers spent around $25 billion online in the 12 months to February 2018, a more than 15 per cent boost over the same period last year, according to the monthly Online Retail Sales Index compiled by NAB.

This equates to eight per cent of spending at traditional bricks-and-mortar retailers, as measured by the ABS in the 12 months to January 2018.

Trend online retail growth is now well above the lows of this period in 2017, and sales volatility dampened in February, the index shows.

The sector saw a 0.8 per cent increase in month-on-month seasonally-adjusted sales, compared to the 0.1 per cent growth seen by bricks-and-mortar retailers.

Growth was mixed across categories, with toys and games and media seeing the biggest increase in online sales, followed by department stores, while grocery and liquor, food catering and fashion sales slowed slightly in the 12 months February, compared to the 12 months to January.

Small and medium businesses represent just over a third of all online sales and saw slightly faster sales growth in February than larger online retailers.