If we are talking about **pure physical strength**, the answer is entirely one-sided: **Superman**. 

Superman is an alien powered by Earth’s yellow sun. He can lift planets, fly at the speed of light, shoot lasers from his eyes, and is practically invulnerable. Batman is just a human—albeit a human in peak physical condition who has mastered various martial arts, but still just a man. In an arm-wrestling match, Superman would win without actually having to flex a muscle.

However, when people ask this question, they usually mean: **"Who would win in a fight?"** 

In the comic books and movies, the answer to that question comes down to one major factor: **Preparation Time.**

Here is the breakdown of how a fight between them works:

**How Superman Wins:**
If the two were to just bump into each other in an alley and Superman genuinely wanted Batman dead, the fight would be over in a millisecond. Superman could punch Batman's head off before Batman's brain could even register that Superman had moved. Superman wins any spontaneous, unprepared fight.

**How Batman Wins:**
Batman rarely fights unprepared. He is heavily considered the greatest tactical mind in the DC Universe. If Batman knows a fight with Superman is coming, he has several ways to level the playing field:
*   **Kryptonite:** Batman hoards Kryptonite (Superman's radioactive weakness) and uses it to forge weapons, gas grenades, and armor.
*   **Red Sun Radiation:** Superman loses his powers under the radiation of a red sun. Batman has built arenas and weapons that simulate this to strip Superman of his powers.
*   **Mech Suits:** Batman has billions of dollars and builds massive, heavily armored battle suits to absorb Superman's blows.
*   **Psychology:** Batman knows that Clark Kent is fundamentally a good person who does not want to kill anyone. Batman uses Superman's own morality against him, knowing Superman will always hold back. 

**The Verdict in Pop Culture:**
In comic book history, they have fought many times. The most famous fight is in Frank Miller’s classic comic *The Dark Knight Returns* (which inspired the movie *Batman v Superman*). In that story, Batman uses a mechanized suit, a city’s power grid, a Kryptonite arrow fired by Green Arrow, and Superman’s own reluctance to kill to ultimately beat Superman into the dirt. 

**Summary:**
*   **Physically stronger:** Superman.
*   **In a surprise fight:** Superman.
*   **With time to prepare and a plan:** Batman.
