From USAJOBS Help
The salary range for a position is typically defined by the minimum and maximum salaries associated with the pay grade or pay band for that position. What an agency offers will depend on their pay setting rules and your qualifications. Please see the announcement for specific education and/or experience requirements for the position.
Pay Grade/General Schedule
Announcements are also classified by the Federal Government's General Schedule (GS) pay scale. As a result, announcements usually provide the salary as well as their GS equivalents.
Search: To search for positions by GS Grade Level, specify a low and high GS level using the provided drop-down lists.
For example: To search for positions that fall within the GS-9 and GS-12 levels, select 9 (as the low) and 12 (as the high) values.
Search Results (Refine): To refine your search results by Pay Grade, select a grade level provided in the refine pop-up box.
To review current Federal pay, visit http://www.opm.gov/policy-data-oversight/pay-leave/salaries-wages/ .