A method for determining the degree of polymerization of a polymer is disclosed, the polymer being contained in a sample (2), the method comprising the following steps: a) illuminating the sample (2) using a laser beam (11) and acquiring (100) a Raman spectrum (S) representative of the polymer; b) identifying (110) a peak of interest (Pi) and determining (120) a position (vi) of the peak of interest in the Raman spectrum; c) on the basis of the position of the peak of interest, using a calibration function (ƒ) to determine a degree of polymerization (DP, DE) of the polymer, the calibration function expressing a variation in the position of the peak of interest as a function of the degree of polymerization of the polymer.