Let be the number of change of sign in the first sequence and be the number of change of sign in the second sequence. Then the number of distinct real roots of in the interval is [14] if . Note that a multiple roots count only for one root with this method.

The drawback of Sturm method is that the absolute value of the coefficients increase quickly when computing the sequence. Numerical rounding errors may then affect the result. The alternate method of Budan-Fourier (see section 5.5.2) is less sensitive to rounding errors although it provides less information than Sturm method.