The heaviest version of Brahmos the Land attack version weighs 3 tons at the time of launch. Much of this weight is fuel which will be consumed in flight.
At impact on target we assume that the missile has consumed 1 ton of fuel and weighs 2 tons and impacts at maximum speed of mach 3 or 1020.87 meters per second.
The above assumptions give us kinetic energy on impact as follows.

Now converting that kinetic energy into equivalent of TNT gives us the following figures.

Based on above calculations, the impact of Brahmos with the target will produce 250 kilos TNT equivalent explosion. Then the warhead the missile carries is 200 kilos for land attack version.
That's total explosion of 250+200 = 450 kilos of TNT.
At impact on target we assume that the missile has consumed 1 ton of fuel and weighs 2 tons and impacts at maximum speed of mach 3 or 1020.87 meters per second.
The above assumptions give us kinetic energy on impact as follows.

Now converting that kinetic energy into equivalent of TNT gives us the following figures.

Based on above calculations, the impact of Brahmos with the target will produce 250 kilos TNT equivalent explosion. Then the warhead the missile carries is 200 kilos for land attack version.
That's total explosion of 250+200 = 450 kilos of TNT.