A method determines an alcohol content of liquids that contain at least water and alcohol as well as sugar or similar substances, in the liquid. The liquid is located in an analysis cell is irradiated by an IR-LED light source, which emits infrared radiation with λ=1000-1500 nm. The IR light absorption is measured at least two different wavelengths, and the measurement values are converted into data on the alcohol content of the liquid. The liquid is irradiated with a first IR radiation with a wavelength λ1, where the absorption coefficient of the alcohol, and the absorption coefficient of the water, are identical in magnitude, and with at least a second IR radiation with a wavelength λ2, where the absorption coefficients and are different. The absorption measurement values determined by an IR detector are applied to a calculating unit for the calculation of the alcohol content.