A detailed comparison of the performance of direct and indirect methods for measuring the hydrocarbon dew point (i.e., the temperature at which the condensation of hydrocarbons in a gas mixture first occurs) of a range of real natural gases and synthetic natural gas mixtures is presented. Good agreement is found between the results of the different methods, although a difference is observed between those from the synthetic gas mixtures and the real natural gases, where the relative order of the dew points determined by direct and indirect instruments is reversed. The relationship between measured hydrocarbon dew point and the condensation rate of the gases is investigated. Using an automatic chilled mirror instrument to measure the dew point of gases with low condensation rates can result in a discrepancy of up to 2 K when compared to the measurement of fast-condensing gases. The limitations of the indirect gas chromatography methods, particularly the difficulties in measuring hydrocarbon species containing 10 or more carbon atoms, have been modeled and can also result in a discrepancy of up to 2 K when compared to the measurement of gases containing no such C10+ species. The magnitude of these discrepancies is close to the uncertainty of the method.