Source: USGS

For the first 1.1 million free Landsat scenes, users had to download one scene at a time. The Landsat Project has developed a bulk download tool so users can more easily download entire lists. After uploading a list of Landsat Scene IDs, scenes that are available on-line can be immediately downloaded. For those scenes that need to be processed, a link is provided directly into our EarthExplorer ordering system (there is no charge for processing). GloVis, EarthExplorer, or user-generated Landsat Scene ID lists can be used. Please go to http://landsat.usgs.gov/Landsat_Search_and_Download.php for more information.