The 180º 13C decoupler pulse using a shape pulse is usually calibrated from the shape 90º 13C decoupler pulse calibration parameters set-up. Alternatively, it can also be measured from a variant of the classical four-pulse HMQC train. Following the same procedure as described for shape 90º 13C decoupler pulse calibration, change the pulse program to dec180sp and reach the minimum signal intensity for the satelite lines by varying the p14 value.