https://en.wikipedia.org/wiki/B61_nuclear_bomb#:~:text=Believed%20to%20be%20either%200.3,kilotons%20in%20its%20various%20mods.Basically, you can make each bomb have a very modest yield, or a very high yield.
Yield = how much boom.
For example, one of the latest versions, you can choose the bomb to have a yield of 0.3, 1.5, 10, or 50 kilotons.
1 kiloton = 1,000 tons of TNT
So, 50 kt would be roughly equal to 200 million sticks of dynamite
(one stick = 0.5 lbs, 2,000 lbs in a ton, 1,000 tons in a kiloton) 50kt * 1000 tons * 2000lbs * 2 sticks per pound = 200 MM
Lowest setting would be 1.2 million sticks of dynamite.
It makes the bombs flexible.