The best way to accurately photometrically calibrate HAWK-I images is to use 2MASS stars in the field itself to derive the photometric solution. The accuracy strongly depends on the number of bright 2MASS stars within the filed of view, but ranges from a few 1/100th of a magnitude to 0.1 magnitudes if only faint stars are contained in the field. Additionally, observing supplementary standard star fields can be asked for when preparing the observations. The new pipeline to be released in 2014 will automatically perform 2MASS photometric calibration on all images.