next exmaple:
First I will make sevral general assumptions:
1. Leopard-2A4 turret have frontal volumen 25% bigger then T-72B.
2. BUrlinghton style armour in Leopard-2A4 have mass efficiency -at lest 1,5 x kg vs KE and at lest 3 z kg vs HEAT -according to the data from 1978, and posted in two greate articles about erly Burlinghton ( I've already quoted them before)
3. The same mass efficiency is taken for T-72B "NERA style" special armour -maybe it's revaluation but I'd rather prefer to overestimated soviet tank then understimated.
4. In T-72B 80% turret mass is taken for frontal protection (+/- 30.degree) - rest (20%) of nacked turret mass is taken for roof, rear sides and turret back. So from 8 680kg it give 6 950kg (inluding NERA special armour). Both NERA armour inserts weight 740kg, so rest of turret armour weight 6 210kg.
5. From known Leopard-2A4 "special armour mass" 8 900kg ~22% is taken for turret sides, so only frontal armour (+/-30 -without turret sides) we have 6 942kg
Now small compare:
T-72B 6 210kg of cast steel turret x0.9 as RHA converter = 6 210kg x0,9= 5 588kg. So whole cast steel T-72B turret armour act like 5 588kg RHA. Now "special armour" cavities (both NERA inserts).
Against APFSDS: 740kg x 1,5 = 1100kg, and against HEAT: 740kg x 3 = 2220kg. So those values are RHA equivalent, and we shoud add them to previous mass.
5 588kg + 1100kg RHA= ~6 688 kg stell armour vs APFSDS
5 588kg + 2200kg RHA= ~7 788kg stell armour vs HEAT
Leopard-2A4 turret weigh 16t, special armour weight 8 900kg, 22% of it ist taken for turret sides, so for +/-30. we have only 6 942kg of special armour. Now x 1,5 vs APFSDS and x 3 vs HEAT:
10 410kg RHA vs APFSDS
20 826kg RHA vs HEAT
Now compare for both tanks:
vs APFSDS
T-72B : 6 688 kg stell armour vs APFSDS
Leopard-2A4: 10 410kg RHA vs APFSDS
So leopard-2A4 armour have 35% more kg of steel armour for protection. Even if Leopard-2A4 turret is 25% bigger in frontal area then still Leopard-2A4 is at least 10% better.
vs HEAT:
T-72B ~7 788kg stell armour vs HEAT
Leopard-2A4: ~20 826kg RHA vs HEAT
So Leopard-2A4 have ~63% more kg of steel armour for protection. And even if Leopard-2A4 turret is 25% bigger in frontal area then still Leopard-2A4 is at least 38% better.
btw: in many estimatous T-72B have basic armourlike <540mm RHA vs KE and <630mm vs HEAT if for kg of armour data for Leopard-2A3/A4 are 10% better in first case, and 38% in second case, then Leopard-2A4 armour should be like ~590mm RHA vs APFSDS and...~870 vs HEAT at least if we take only those one factor described above. In fact diffrence in HEAT protection is even bigger -for many causes - for example -Burlinghton features.