In 2024, the average age for personnel in the UK Armed Forces overall was 31 years old. The average age of those serving in the British Army was also 31, with the average age rising to 32 for the Royal Navy and Marines, and was 33 for the Royal Air Force (RAF). The average age for officers in the Armed Forces was 37, with this rising to 38 for officers in the Royal Air Force. Personnel falls to historical lows in 2024 Overall, there has been a long-term decline in the size of the armed forces, with the number of personnel declining from over 200,000 in 2000, to around 138,120 by 2024. In fact, the size of the armed forces has been in almost constant decline since the end of World War Two. Britain's retreat from its colonial empire throughout this period removed many of the UK's overseas commitments, with the end of the Cold War also leading to further cuts to personnel. Operational deaths since the Second World War Since 1945 there have been 7,193 operational deaths in the United Kingdom’s armed forces, with the deadliest year occurring in 1951 when there were 851 deaths. This was due to three separate conflicts: the Malayan Emergency, the 1951 Anglo-Egyptian War and the Korean War. Since 1959, there were only three years that had more than 100 operational deaths: 1972, 1973 and 1982. By comparison, between 2016 and 2024, there have been only nine operational deaths, with just one death reported throughout the whole of 2023.

In 2025, the average age for personnel in the UK Armed Forces overall was 31 years old. The average age of those serving in the British Army was also 31, with the average age rising to 33 for the Royal Air Force (RAF). The average age for officers in the Armed Forces was 37, with this rising to 38 for officers in the Royal Air Force.