Techniques enable locating a position within a file that corresponds to a desired seek time without having access to an index specifying the desired seek time's position. An iterative process may be used to estimate the position that corresponds to the desired seek time. The process may iterate through multiple estimations until a difference between a time corresponding to an estimated position and the desired seek time is within an acceptable amount or until the process reaches an iteration threshold. The file may then be played beginning at or near the desired seek time. The techniques may therefore allow a user to seek within a file while the user progressively downloads or streams the file.