The blast that devastated large parts of Beirut in August was one of the biggest non-nuclear explosions in history, experts say.
The Sheffield University, UK, team says a best estimate for the yield is 500 tons of TNT equivalent, with a reasonable upper limit of 1.1 kilotons.
This puts it at around one-twentieth of the size of the atomic bomb dropped on Hiroshima, Japan, in 1945.
The team mapped how the shockwave propagated through the city.
The group hopes its work can help emergency planners prepare for future disasters.
“When we know what the yield is from these sorts of events, we can then work out the loading that comes from that. And that tells us how to construct buildings that are more resilient,” said Dr Sam Rigby from Sheffield’s Blast and Impact Engineering Research Group.