A quantitative insight is given into the performance of integrated thermopile vacuum sensors as a vacuum gauge. After a short resume of their operation principle three pressure ranges are discussed. The zero repeatability is shown to be approximately 10 mPa. In the optimum pressure range of 1-100 Pa the error of prediction of the sensors is 2-3% while the upper pressure limit of the sensors is of the order of 5-50 kPa. A comparison with conventional Pirani gauges is made.