POINTS FORMULA
A class armour = 36
B class armour = 25
C class = 16
D class = 9
E class = 4
F class = 1

Gun class 1 = 36
Gun class 2 = 25
Gun class 3 = 16
Gun class 4 = 9
Gun class 5 = 4
Gun class 6 = 1

Fast tanks add 10% to points cost, Slow tanks deduct 10% from points cost.

So for a B3 tank formula values calculate as follows ; armour class x gun class divided by 4, then plus 10 which gives a value of 110 I think.
Formula designed using C3 cost of 70 pts as a starting point (Yes I know points come out as 74 with formula).

Where formula works is that it reflects the fact that the combination of guns and armour has more complex effect than simply adding separate points costs for each together.

Where formula falls down is:
1. It gives equal value to survivability and gunpower.
2. The + or - 10% for speed is a bit arbitrary
3. Is not time period specific e.g KV1 in '41-'42 a monster by late'43 not so hot
4. Does not, to paraphrase Lanchester's statistical work, take into account that numbers have a quality all of their own
5. Does not take into account infantry and their AT capability

I think that to put together a better points formula would require running a series of tests using a set of standard scenarios for each period of war. This should deal with the problems I have enumerated above but would be time consuming and dull.

MEDIUM
Gun Class	Armour Class
	A	B	C	D	E
1	334	235	154	91	46
2	235	166	110	66	35
3	154	110	74	46	26
4	91	66	46	30	19
5	46	35	26	19	14
6	19	16	12	11	10

FAST
Gun Class	Armour Class
	A	B	C	D	E
1	367	259	169	100	51
2	259	183	121	73	39
3	169	121	81	51	29
4	100	73	51	33	21
5	51	39	29	21	15
6	21	18	15	13	12

SLOW
Gun Class	Armour Class
	A	B	C	D	E
1	301	212	139	82	41
2	212	150	99	60	32
3	139	99	67	41	23
4	82	60	41	27	17
5	41	32	23	17	13
6	17	15	13	11	10