Three people with knowledge of the matter said Microsoft has sold just over 1 million Surface RT units and around 400,000 Surface Pros since their debuts in October and February, respectively. Three million units were ordered in all, the sources said.
The 32GB Surface RT starts at $500, while the 64GB Surface Pro begins at $900.
By comparison, Apple sold 22.9 million iPads in the three-month period ended December 29.
In an effort to boost Surface sales, Microsoft will take steps to market the tablet line in new ways, the sources said. One source added that Microsoft has internally admitted a failure to persuade some customers to choose Surface over offerings from Apple and Samsung.