There are, at least, a few ways to measure the damage a weapon can do. Perhaps the simplest, and most easily transferred between varying weapon types, is the energy behind the blast. This is often normalized per kg because you can often get bigger explosions by simply adding more explosives. Another good way is to measure the energy in terms of how much TNT you would need to produce that energy.
TNT (the explosive) has an energy of 2.8 megajoules per kg. Dynamite is at 7.5 megajoules per kg, or about 2.67 times as explosive as TNT. Let's talk about kinetic rounds.
Kinetic rounds do not use explosive force, but they do carry the common currency of energy. Obviously, kinetic rounds use kinetic energy, not "explosive" energy like TNT. Since both objects are often measured in how much energy they hit the target with, you can make the comparison.
To determine the kinetic energy of something, you use can use:
$$E_{k}=\frac{1}{2}mv^2$$
Where m is the mass of the object and v is it's velocity.
For Jupiter, going at the speed of a bullet from a high-powered rifle (mach 1), gives you about $1.09899149 × 10^{32} J$. That is $3.925 * 10^{25}$ kg of TNT. However, Jupiter is so big that this speed is really slow. Jupiter orbits at $13\frac{km}{s}$, whereas the speed of sound is a measly $.340 \frac{km}{s}$.
If you shot jupiter at .1c, one-tenth the speed of light ($2.998*10^{7} \frac{m}{s}$), you get $8.530 * 10^{41} J$. That is $3.046 * 10^{41}$ kg of TNT.
For reference, the Tsar Bomba, considered the most powerful man-made explosion in the world, was 50 megatons of TNT. That is 209.2 PJ ($209.2 * 10^{15}$ J). That also assumes that nothing else blows up when Jupiter hits, as it's mostly (~89%) $H_2$. (Oxygen is not naturally present in large amounts in Jupiter, so it would not explode like the Hindenburg did.)
