The invention relates to a method and a device for measuring a layer thickness of an object. Firstly, an object which has a layer thickness is provided. Subsequently, at least two measurement steps (Mi) are carried out, wherein in each case electromagnetic radiation with frequencies (f) in a frequency band (Fi) corresponding to the measurement step (Mi) in question is radiated onto the object. The frequency bands (Fi) are different partial regions of a bandwidth (B). Secondary radiation emitted by boundary surfaces of the object is detected and a measurement signal corresponding to the measurement step (Mi) is determined. The measurement signals are, according to the frequency bands (Fi) corresponding to the measurement steps (Mi) in question, combined to form an evaluation signal, a base frequency is determined therefrom, and the layer thickness is calculated. Using the method, a large bandwidth (B) can be realised by means of narrow-band measurement steps (Mi). In so doing, physical limits of known methods are overcome and the measurement accuracy is increased.