Hard real-time systems have stringent timing constraints expressed in units of time. To ensure that a task finishes within its time-frame, the designer of sucha system must be able to derive upper bounds on the task's worst-case execution time (WCET). To compute such upper bounds, timing analyses are used. These analyses require that information such as bounds on the maximum numbers of loop iterations are known statically, i.e. during design time. Parametric timing analysis softens these requirements: it yields symbolic formulas instead of single numeric values representing the upper bound on the task's execution time. In this paper, we present a new parametric timing analysis that is able to derive safe and precise results. Our method determines what the parameters ofthe program are, constructs parametric loop bounds, takes processor behavior into account and attains a formula automatically. In the end, we present tests to show that the precision and runtime of our analysis are very close to those of numeric timing analysis.