According to the Official Handbook Of The Marvel Universe, Iron Man can lift 75–100 tons. There are plenty of characters who are in the 100 ton plus league, like Thor, Hulk, Hercules, Thanos and Gladiator, among others, but, his strength is still impressive.
The Extremis armor increases Stark's strength to the point that he is able to lift up to 100 tons, the same as a calm Hulk.
Using The Suit, Tony Stark Can Lift In Excess Of 100 Tons
Although the initial versions of the suit were limited in their strength, later models have proven incredibly powerful.
Strength level: Without his armor Tony Stark possesses the normal strength of a normal human man his age, height, and build who engages in moderate regular exercise. His armor magnifies Stark strength to superhuman levels, enabling him to lift (press) roughly 85 times.
Enhanced Durability: The Iron Man suit is extremely resistant to all kinds of punishment. The armor can easily withstand bullets. It can also withstand rockets, missiles, electricity, fire, extreme temperatures, high-powered lasers, heavy impacts, energy attacks, and such with only minimal damage.
Captain America is physically stronger than Iron Man, whether with his suit or not. If they both entered a ring-to-box hand-to-hand combat, Captain America would destroy Iron Man in that fight. However, if we consider all features in their respective arsenals, Iron Man would literally toast Cap.
The Iron Man Armor Mark LXXXV was the most advanced and powerful armor Tony Stark has ever created.
How high that strength level rises would vary in different comic books, but most classify Thor in the “Class-100” strength category, which means he can lift well over 100 tons without too much difficulty.
The weakest suit of Iron Man and the strongest
The weakest suit ever worn by the superhero has to be the very first one – Mark I, though it had enough strength to help him get out of the caves where he was held captive, it was no match to the suits that followed. It was built using whatever Tony could find in the cave.
Strength Level: The Hulk possesses superhuman strength of the Class 100 level, enabling him to lift (press) in excess of 100 tons. The Hulk only attains this strength level when he is enraged. In a totally, calm state his functional strength is significantly less, perhaps in the 70 ton range.
The Hulk: 11 million lb.
In the MCU, he's rarely seen lifting solid objects; he usually winds up smashing them instead.
Strength. Captain Marvel can lift 200 tons when in Binary mode—a hefty 400,000 pounds that is well over the combined lift of Cap, Iron Man, Widow, Black Panther, Scarlet Witch, Vision, Ant-Man, the Wasp, Doctor Strange, and Hawkeye.
Assuming a proportional relationship between grip strength and what the average male American can lift, back-of-the-envelope math suggests Thanos could heft 120 million pounds, 10 million pounds more than the weight of the Titanic.
Colossus' incredible strength class is 100+, which means he can consistently lift above 100 tons. Colossus' most ridiculous feats in the comics further prove his elevated strength class.
Presumably, then, Thanos possessed at least Class 100 strength, enabling him to lift (press) over 100 tons. Known Superhuman Powers: Thanos possessed incalculable superhuman power.
Great Power. Like his namesake, Spider-Man's strength and agility stand far above those of the average human, allowing him to lift nearly ten tons and to leap and move at incredible speeds with high accuracy.
Given his mastery of the magical arts, it would make Doctor Fate a tough opponent for Iron Man, whose technology-based weaponry would be ineffective against his magical defenses. Moreover, with his vast mystical powers and abilities, Doctor Fate could quickly neutralize Tony Stark and take him down in battle.
In both Marvel Comics and the MCU, Iron Man is no pushover, but one story showed that even with his full arsenal, he can be taken down singlehandedly by the Guardians of the Galaxy's Gamora.
Mandarin - The archenemy of Iron Man, the Mandarin is a Chinese nobleman, scientist and former diplomat turned criminal mastermind.
He gained many abilities. Godlike strength: Thor has limitless strength and can power himself even more by charging himself with lightning. He was able to bend Captain America's shield, then bend it back perfectly back to shape. He's the second strongest Avenger.
This difference in gravity allows Superman to lift objects that measure in the tons. In fact, the comics have put Superman's strength at a point where he's able to lift around 2 billion tons! To put that into perspective, the Empire State Building is only 365,000 tons!
STRENGTH LEVEL: Captain America represents the pinnacle of human physical perfection. While not superhuman, he is as strong as a human being can be. He can lift (press) a maximum of 800 pounds with supreme effort.
So, when Thanos was about to use the powers of Infinity Stone to kill Iron Man, despite stabbing him already, it was because he did not wish to leave any chance of him surviving. Ironically, it was Tony Stark who defeated Thanos five years later in Avengers: The Endgame.
Iron Man's armor has proven potent against many foes, but he's never created a suit of armor that has allowed him to defeat Thanos. Like many others, Iron Man is frightened of Thanos, and for good reason. He's never beaten him.
However, the majority of the more-advanced suits, starting with Mark III, were made not of iron but of a titanium or titanium-gold alloy. In the 2019 film Avengers: Endgame, the suit was constructed of vibranium and nanotech.