Depends on what tank you are referring to. The M1A2 Abrams tank has 120 mm (4.72 inches) of armour.
M1A2 is the more advanced model.
M1A2 Abrams. 68 tons of steel.
M1a2 stats: 125mm smoothbore cannon,1500 hp and manual loader
The biggest tank in the world would probably be the US M1A2 Abrams main battle tank.
It is among the most advanced in production, though it's not the only such tank in existence.
120mm smoothbore tank ammo, 12.7x99 (.50 BMG), and 7.62x51.
The M1A2 costs $6.21 million per, although there have since been upgrade programmes which have likely made the tank more expensive.
this answer is not ture for many reason one. the m1a1 is a out dated verison of the m1a2 and the most advanced tank in the world is the British Challenger 2
The Challenger. Although the Abrams is one of the three best in the world, the Challenger has greater accuracy, greater offroad speed, superior armour and improved firepower. American tank armour is made by a British company and acted for the Challenger's armour's prototype. Challenger armour has been improvd twice since then.
M1A2 and M1A1 Abrams. There MIGHT still be some M60A3 tanks in use with the National Guard.
The cost is around 4 million.