I'm wondering about the total megatonnage of all munitions expended during World War Two in all theaters.
I've seen estimates of 2, 3 and 5, but no concrete cited sources for a specific number.
3 megatons. The Source I've seen quoted in several places is the one calculated by the Center for Arms Control and Non Proliferation given below.
Bulletin of the Atomic Scientists
The total blast power of World War II has been calculated as three megatons by the International Commission on Nuclear Non-Proliferation and Disarmament.
The total energy of all explosives used in World War II, including the Hiroshima and Nagasaki atom bombs, is estimated to have been three megatons of TNT.
ARMS CONTROL: PRESERVING PEACE FROM NUCLEAR THREAT
set off in World War II into one huge blast, it would merely be equal to three megatons and would be even less powerful than one of today's nuclear bombs.
'NOVA' EXAMINES 40 YEARS' NUCLEAR POLICY
In World War II, the equivalent of 3 million tons of TNT - three megatons - were exploded. The world's nuclear arsenal today is estimated at 15,000 megatons.
Center for Arms Control and Non Proliferation: Fact Sheet: The Nuclear Triad
all explosives dropped during the six years of World War II, including the two nuclear weapons, equaled three megatons.