So this blog attempts to answer an interesting question: at what level do characters become completely immune to conventional bullets? Insofar as VSBW goes, this is not very useful because most weapons act far more powerful than they really should be and/or are magical, but it could be useful if comparing certain characters to real life statements.
Note that because this wiki considers durability to apply equally over the body, I will simply be using the surface area of a human body and comparing it to that of a bullet tip. However, it is entirely possible for certain points of the body to have lesser durability, such as the eyes, so keep that in mind as well.
The largest caliber round in the world is the 0.950 JDJ. This gives us a good high end to use. Now, to find the size of the 0.950 JDJ tip, I will have to scale from an image.
Scaling:
Bullet diameter = 24.1 mm = 191 pixels
Bullet tip diameter = 7 pixels = 0.883 mm
Treating the bullet tip as a perfect circle, we get a surface area of 2.4508 x 10^-6 m^2. Compared to the average human male surface area of 1.9m^2, this is a 775,247x difference.
Now all we need to do is find the maximum energy delivered by this bullet. For the sake of keeping to a high end calculation, I will not use the muzzle velocity of the 0.950 JDJ but rather the max possible - that of the lowest weight of the 0.220 swift. This equates to a muzzle velocity of 1284 m/s.
Plugging that velocity and the weight of a 0.950 JDJ (0.233 kg) into the KE equation, we get a total energy of 192,068.424 Joules. Multiplying by the surface area difference, we get the following amount for the minimum required to be invulnerable to all realstic bullets:
1.489 x 10^11 Joules or City Block level.