In the United Kingdom, all branches of the armed forces use 2.4-km run time and/or the 20-m multistage shuttle run test (MSRT) to assess the aerobic fitness of their personnel. This study quantified the relationship between these two tests in 156 army recruits and officer cadets (100 men and 56 women) to ensure equivalence in the required aerobic fitness standards. The 2.4-km run was performed on surfaced roads and tracks around the training establishment and the MSRT in a gymnasium. Ordinary least product regression was used to describe the relationship between average 2.4-km running speed (km.h-1) and the total number of shuttles completed on the U.K. version of the MSRT (r = 0.91, p < 0.01), showing MSRT shuttles = (9.708 2.4-km run speed) - 52.56, with a standard error of prediction of approximately 8 shuttles or 0.8 km-h-1. The British Army 2.4-km run biannual fitness assessment standard for young men of 10:30 min:s equates to a MSRT score of 82 shuttles (level 10 and 1 shuttle) and for young women of 13:00 min:s equates to 56 shuttles (level 7 and 6 shuttles), with a standard error of estimate of approximately 8 shuttles.