In a number of recent publications, a one-dimensional effective model for quantum transport in a nanotransistor was developed yielding qualitative agreement with the trace of an experimental transistor. To make possible a quantitative comparison, we introduce three phenomenological parameters in our model, the first one describing the overlap between the wave functions in the contacts and in the transistor channel, the second one is the transistor temperature, and the third one is the maximum height of the source-drain barrier. These parameters are adjusted to the traces of three experimental transistors. An accurate fit is obtained if the three adjustable parameters are determined for each gate voltage resulting in three calibration functions. In the threshold- and subthreshold regime the calibration functions are physically interpretable and allow one to extract key data from the transistors, such as their working temperature, their body factor, a linear combination of the flat band voltage and the built-in potential between substrate and source contact, and the quality of the wave function coupling between the contacts and the electron channel.