“Rule 07,” a simple empirical relationship, conveniently estimates state- of-the-art HgCdTe dark current performance over 13 orders of magnitude, covering wavelength ranges form short-wave infrared (SWIR) to long-wave infrared (LWIR), from room temperature to liquid nitrogen temperatures. The best HgCdTe, in some cases, approaches the external radiative limit of performance, but is typically two to three orders of magnitude above that, being limited by defect generation centers as yet unidentified and/or by Auger mechanisms. The empirical relationship represents the range of detectors fabricated at Teledyne using our molecular beam epitaxy (MBE)-based double-layer planar heterostructure (DLPH) technology, but also appears to characterize good detectors from other laboratories.