Introduction
At the moment, Samurai Jack is "at least 7C" for several feats. However, these feats either have no calculation, or are not impressive at first glance. Can any of these hold up? Let's see.
The Feats
 1. Destroying a Town: In Season 1 Episode 11, Samurai Jack and Scotsman destroy a town. But... they did it over a VERY long time. Tons of fighting takes place, and eventually the town is destroyed. This is not indicative of town level, as town level implies you can hit with town level power in either a second and/or a single strike. In fact, the only showing of any direct destruction is when 7 wooden houses collapse after the fighting. Even if each of these small wooden shacks took baseline building level power to destroy (which I doubt), it wouldn't even break into High 8C. And that is STILL assuming they caused that in one shot, which is never shown and implied to be the contrary. If all of this isn't enough, they did it together, in addition to many enemies. Any result would be divided, at minimum, by two. This isn't worth calcing, considering the other feats should break this.
 2. Destroying a Forest: In Season 1 Episode 8, Jack and Mad Jack destroy a forest (Seizure warning on that one; that really hurt my eyes). In their final clash, Jack and Mad Jack create an explosion that starts to destroy the environment around them. This could certainly be promising, and I'll see what results it gives using the explosion formula as well as temperature increase.
 3. Ultra Robot Destroys part of a City: In Season 2 Episode 5, the Ultra Robots destroy a City. We see one unleash a devastating fire attack, which burns everything and even melts metal. Since this is directly stated to be a fire attack, I will use temperature increase, not explosion formula.
 4. Jack Survives Atmospheric ReEntry: In Season 1 Episode 5, Jack get pushed by explosion into Earth's gravity field, and falls back to the surface. He lands, hitting the ground with massive force and creating an explosion. For this I'll calc the durability needed to tank the landing, KE wise. The explosion will be inconsequential next to this energy.
The Calculations
These are going to be raw to save time. Explaining these in full would take many hours to write up. Edit: Actually this took several hours anyway.
Forest Destruction






Jack: 10.49 pixels
Small screen: 165 px
Big Screen: 480 px
Jack height real: 178 cm
Small Screen Distance:
2atan(tan(70/2)*(10.49/165)) = 0.06022804697 radians
0.06022804697*180/pi = 3.45081289981 degrees
Distance: 2954 cm, 29.54 meters
Big Screen Distance:
2atan(tan(70/2)*(10.49/480)) = 0.0207089116 radians
0.0207089116*180/pi = 1.18653323334 degrees
Distance: 8595 cm, 95.95 meters
Heat Yield
Average temperature: 293.15 Kelvin
Ignition of Wood: 573.15 Kelvin
Temp change: 280 Kelvin
Low End:
Hemisphere volume: 5.4x10^4 cubic meters
Air density at room temp: 1.225 kg/m^3
Air mass: 66150 kg
Energy: (66150 kg)*(717.8 J/kgK)*(280K) = 1.329x10^10 joules
High End:
Large hemisphere volume: 1.85x10^6 cubic meters
Air mass: 2266250 kg
Energy: (2266250 kg)*(717.8 J/kgK)*(280K) = 4.555x10^11 joules
Explosion Yield:
Much lower. Not worth it. See this for more info.
 Note: I used the shown screen size as well as the normal screen size. They zoomed into cinematic mode so I figured I would give the benefit of the doubt and use normal screen as well. Not sure if it is valid, but it is there.
Ultra Robot Melts City












Scaling
Jack height: 178 cm
Jack head real : 22.25 cm
Jack head: 55 px
Pixel: 0.404 cm
Height difference: 18 px
Height difference real: 7.272
Ultra robot height: 170.728 cm
UR leg height: 15.87 px
UR body height: 13 px
UR full height: 28.87 px
UR real height: 170.728 cm
Pixel: 5.917 cm
Blast diameter: 636 px
Blast radius: 318 px
Blast radius real: 1881.606 cm, 18.816 meters
Volume and Mass
Hemisphere volume: 13938.79 cubic meters
Air density: 1.225 kg/m^3
Air mass: 17075.01775 kg
Heat Energy
Average temperature: 293.15 Kelvin
Steel Melting Point: 1643.15 Kelvin
Temperature increase: 1350 Kelvin
Energy: (17075.01775 kg)*(717.8 J/kgK)*(1350K) = 1.655x10^10 joules
Atmospheric Reentry
Space suits weigh 310 lbs, or 140.614 kg. Assuming Jack weighs 70 kg: Combined weight: 210.614 kg
Jack Tanks atosphereic reentry
Mesosphere entry: 3:01.42
Touchdown: 3:07.94
Timeframe: 6.52 seconds
Mesosphere height: 85 km
Speed: 13.037 km/s, 13037 m/s, 163% faster than standard reentry speed of 8 km/s
Mass: 210.614 kg
KE: 0.5*210.614*13037^2 = 1.790x10^10 joules
Final Tally
Forest Burning Low:1.329x10^10 joules or 3.176 tons of TNT, High 8C, Large Building level
Forest Burning High: 4.555x10^11 joules or 108.867 tons of TNT, 8A, MultiCity Block level
Ultra Robot City Melt: 1.655x10^10 joules or 3.956 tons of TNT, High 8C, Large Building level
Accelerated Atmospheric Reentry: 1.790x10^10 joules or 4.278 tons of TNT, High 8C, Large Building level
I personally prefer the low end of forest burning. I know it is legit, and it is stupid consistent. Like all of these except the potentially dubious high end are within 35% of each other. Crazy consistent.