An antimatter bomb would be pretty powerful and can release the same amount of energy as a nuclear bomb.
The amount of power than an antimatter bomb would have would be directly related to the amount of antimatter being used.
Even a small amount of antimatter being used for an antimatter bomb it would produce a tremendous release of energy.
One gram of antimatter that reacts with one gram of ordinary matter would release the same amount of energy as a nuclear bomb which would be around 21.5 kilotons of TNT.
A lb of antimatter in contrast would also produce an explosion that would be equivalent to 20 megatons of TNT.
The energy that is released by antimatter annihilation is also considered the densest form of energy release that is known.
Antimatter is a substance which is composed of antiparticles that are counterparts to ordinary particles such as electrons and protons, but with opposite electric charges and other quantum properties.
And when matter and antimatter meet, they then annihilate each other and convert their mass into energy, which is often in the form of photons "light", or other particle-antiparticle pairs.