A horizontal comparison is made between the four laboratories that certify Charpy impact verification specimens. The participants in this study were Japan (NRLM), France (LNE), the European Commission (IRMM), and the United States (NIST). The exercise was conducted to show how the impact verification programs, specimens, and test procedures compare with each other. Results for both 8 and 2 mm strikers were compared. The study showed the following: (1) The certified energies of impact verification specimens distributed by these four metrological authorities often agreed within 1% of the average values determined in this study; (2) the variation in energy for the specimens was low, typically bracketed by a coefficient of variation of between 0.02 and 0.04; and (3) the energies measured for the tests performed with 2 and 8 mm strikers on the 4340 steel specimens were nearly equivalent, but a trend of slightly higher energy for the 2 mm tests is indicated.