While the MOAB is the largest conventional bomb used by the U.S., Russia tested the "Father of All Bombs" (FOAB) in 2007, which is claimed to have a blast yield four times greater than the MOAB, though specifications are disputed.
https://arxiv.org/html/2602.02470v1
While the MOAB is the largest conventional bomb used by the U.S., Russia tested the "Father of All Bombs" (FOAB) in 2007, which is claimed to have a blast yield four times greater than the MOAB, though specifications are disputed.