Where to start?  This epic project has taken such a long time, but I have enjoyed doing it.

What it does:  At a glance, you can tell how vulnerable a vehicle is to fire from an enemy gun.

How to use it:  Using the drop down boxes (not the ones above, it is a simple image, not the program itself!) you select an allied and axis vehicle, tank, or towed gun.  On the inner drop down boxes you select the ammunition type and date.  In the graphs above, you can read the vulnerability of each vehicle to the enemy ammunition. 

How to read the graphs:  These are 360° representations of the vehicle, the front is always at the top, the rear is always towards the bottom of the page.  Let's take the above "Upper Hull" graph with a grey background.  This represents the vulnerability of the upper hull of the Panther to the ammunition shown in the yellow strip below.  The graph shows performance out to 2000m.  The graph compares the gun's penetrative power referencing the ammunition used, at range, versus the armor plate selected.  Simply put, if a hypothetical gun can penetrate 105mm of armor at whatever range and is striking a 100mm plate, it has 105% the required power.  That does not necessarily mean a penetration or a kill, keep reading.

In this "Upper Hull" graph, you can see that the Panther is vulnerable to enemy fire to beyond 2000m.  The IS-2 can penetrate some part of the Upper hull of the Panther if firing at 2000m, as long it is at least 40° from the front of the vehicle.  These charts show WHICHEVER PANEL IS MOST VULNERABLE.

Also consider:

• Just because a vehicle is outside effective range does not mean it cannot eventually destroy a vehicle.  I once attacked a KV with a few PzII.  In the game roughly 1 in 20 rounds causes damage.  I surrounded the KV and ordered them all to open fire.  I lost some, but the hail of 2cm rounds, which had no chance of penetrating, ripped off the tracks and destroyed some component of the gun system.  The crew of the immobilized and nearly unarmed KV finally abandoned it.  (Remember that some MGs can still fire, be careful when assaulting with infantry.)
• A penetration does not mean a kill.  A vehicle at a slight disadvantage in probability of penetration that is firing AP with a large explosive component can easily wipe out a vehicle that is firing a solid shot like APRC.
• These charts do not show accuracy or rate of fire.  That is another chart which is a free download also listed on this page.  (I need to list an updated one, that one is years old!)
  

THE OTHER CHARTS SHOW THE INFORMATION FOR THE OVERALL VEHICLE, TURRET, UPPER AND LOWER HULL, FOR BOTH VEHICLES.
This tool is also great for comparing ammo.  For example you can switch between the Soviet AP and APBC ammunition... and find that it is much more lethal against the Panther.

Things I have corrected thus far, and now work correctly:

• Vehicles without turrets, like the Jagdpanther, work correctly and simply do not display any possibility to penetrate the turret.
• Vehicles with open, unarmored areas- like the Marder, show red from any angle which fire can enter that unarmored space.

Limitations I am correcting (with some help), but require tremendous work:

• For the most part it includes all German and Soviet Guns, Vehicles, and Tanks.  I have included some equipment from other nations, but want to make it all inclusive.  As soon as I get to it in spite of all the other projects!  CMAK DATA IS NOW INCLUDED!!!!
  

A limitation that I will not correct (because it is not modelled in the game, and this calculator is built for the game)... and it'd be really, really hard to do!:

• Items where the armored plate is not a simple box like a KV-2 or Jagdpanther are not completely correct.  Rounded turrets, like a BT-2 or Tiger, still show the obliquity angle even though the turret face is round.  The front of the IS-3 hull still shows like a traditional hull, and does not take into account the 'pike' nose.  Tests have shown that the game uses everything having rectangular turret and hull models.
  

Status:  The program is complete.  I am just entering all of my data which is taking a long time, but I am nearly done. 
Purchase price is $19.99, simply a donation to my website to help me loose less money on it!  ($20 pays for a month for me!)  I will email the file to you. 
CLICK THE DONATION BUTTON BELOW, AND ENTER $19.99, THAT'S MY CODE TO KNOW YOU WANT ME TO SEND THIS FILE TO YOU.
As new data gets entered I will send out new versions of the file as soon as they are complete.  I WILL SEND OUT REVISIONS FREE OF CHARGE!

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This pic of part of one of my spreadsheets gives a ton of data I have collected on the Panther series of tanks.  The impact data (left chart) shows, from direct front, where the rounds strike the tank, this is from 1555 impacts, so it's pretty significant... and it took a long time.  I also tested to see if perhaps the percentage of the upper hull hits increased and lower hull hits decreased with range because of the higher trajectory of the rounds, it does not, even with slow rounds (top chart). 

Lastly (bottom chart) I show a somewhat statistically significant chart breaking down upper hull penetrations.  This data was the purpose for this entire exercise.  I placed the Panther tanks at 900m, the range that my new parabolic equations suggest that the UH armor of 100% quality will be right at the maximum yield of 100mm AP.  Sure enough, those that struck the early Ausf A almost never suffered any penetrations.  The "occasional flaws" of the late Ausf A allowed many more partial penetrations, including a few full penetrations.  "Frequent Flaws" in the G model glacis allowed frequent penetrations in this test model; 4 times as many full penetrations.  Now, I understand that 562 hits is hardly stat-sig, but it gives a clear view of how the Panther glacis plate is modeled in CM, and I think it is probably modeled very well.  I am impressed that they took the time to single out this problematic part and model it with (reasonable) historical accuracy!  I'll do the math to approximate the 'armor quality' percentage that was probably applied sometime soon.  I bet I can figure out Rexford's standard deviation / penetration percentage data to do this... but right now it's 4:30am and my brain's melted!

As a side project you can see in the data that I kept track of turret hits.  Though not totally stat-sig, I noticed that there were no "penetration at weak point" for the G, late turret, and wondered if these weak point penetrations were how CM handles the shot trap.