AFV Scaling Calculator
(Created 21 May 2016)
(Finally Uploaded 27 Jan 2018)

This page will calculate crude armor protection values for a tank, given an approximate mass in metric tons. Essentially, you can use it to scale a design up and down -- e.g. what would the armor protection of a 15 ton light tank designed like the Panther be? It will also tell you the rough firepower you can safely put on that vehicle in operational terms.

The armor scaling is based off a simple equation found in an article by R.M. Ogorkiewicz titled "Thoughts on...FUTURE TANK DESIGNS" in ARMOR magazine (the US Armor community's official journal), and evolved somewhat from that.

At first, I was skeptical that a simple linear equation could model tank armor thicknesses, but the following graph below was pretty instructuve (it illustrates frontal hull thickness).

The Evolved Equation is:

T = ( E * W ) * A


T = Horizontal thickness of frontal hull armor in millimeters.
E = Efficiency of hull design.
W = Weight (Metric Tons)
A = Aspect Correction Factor (1.0 = frontal armor).

To compute E, you have to have the tank mass in metric tons; plus detailed armor schematics/angles, in order to find a correct E number for that design ethos. In general, tanks with straight sides will have lower E numbers, while tanks with excellent sloping will have higher E numbers. Additionally, higher E numbers also mean the tank is significantly more cramped, with certain limitations on gun elevation/depression, such as in post-war Soviet/Russian Tanks.

Maximum gun power was derived from a line in Richard M Ogorkiewicz's Technology of Tanks where he says:
So far as the crew are concerned, there is a rough empirical rule that the ratio of the impulse to the mass of the vehicle should be no more than about 900 Ns/ton. As it happens, for most recently built tanks this ratio has had a value of between 500 and 700 Ns/ton. The few where the ratio exceeded 1000 Ns/ton, as it did in the US M551 light tank when it fired its heavy 152mm HEAT projectiles, have been considered very uncomfortable for their crews.

From that, I figured out that "average" tank recoil ratios were:

Weight (metric tons):

Turret "E" Value:
Turret Side "A" Value:

Hull "E" Value:
Hull Side "A" Value:

Load Pre-Determined Settings

Comfortable Gun Power Level MJ.
Dangerous Gun Power Level MJ.

Turret Front Armor mm RHA(e).
Turret Side Armor mm RHA(e).

Hull Front Armor mm RHA(e).
Hull Side Armor mm RHA(e).

Gun Power (representative)

50mm L60 KWK.38 (0.72 MJ)
75mm L37.5 M3 (1.21 MJ)
75mm L48 KWK.40 (2.14 MJ)
75mm L70 KWK.42 (3.18 MJ)
88mm L56 KWK.36 (3.06 MJ)
90mm L70 T15E2 (5.19 MJ)
88mm L71 KWK.43 (5.25 MJ)
105mm L50 M68 (6.32 MJ)
120mm L44 M246 (10.16 MJ)