Robot Solves Rubik’s Cube in 0.637 Seconds?

Yes, a robot has solved a standard 3×3 Rubik’s Cube in 0.637 seconds, a record set in 2018 by a machine built by MIT students. The robot uses a custom vision system to identify the cube’s state and high-speed motors to execute the 21 moves needed for the solve. This article explains how such a fast solve is possible, what the record actually means, and how it compares to human speeds.

Formula

The calculator above estimates the effective turning speed of a robot or human solve. The formula is:

TPS = Moves / Time

Where:

• Moves – the number of quarter or half turns of a face (a half turn counts as one move in standard notation).
• Time – the total solve time in seconds.
• TPS – turns per second, a measure of how quickly the cube is manipulated.

Worked Example

Using the default values from the calculator (0.637 seconds and 21 moves):

1. Divide the moves by the time: 21 ÷ 0.637 = 32.97.
2. So the effective turning speed is about 33 turns per second.

That means the robot executes roughly 33 full face turns every second, which is far beyond human capability.

How the Robot Achieves 0.637 Seconds

The MIT robot, built by Ben Katz and Jared Di Carlo, works in four stages:

• Scanning: Two webcams photograph the cube from different angles. The software identifies the color of each sticker (or facelet) and reconstructs the full state.
• Solving: A computer algorithm (typically Kociemba’s two-phase solver) finds a short solution, usually around 20 moves. The solution is computed in microseconds.
• Executing: The robot’s six arms, each with a stepper motor, turn the faces. The motors are powerful and the arms are lightweight to minimize inertia.
• Stopping: The cube is held in place by the arms, and the solve ends when the last move is completed. The timer stops automatically.

The 0.637-second run used 21 moves, giving a TPS of about 33. The robot’s design prioritizes speed over precision; it does not need to stop between moves because the cube is never released.

Comparison with Human Speeds

The fastest human solve of a 3×3 cube is just over 3 seconds (set by Max Park in 2023). The average speedcubing champion solves in 5–6 seconds. Humans turn the cube at about 10–12 turns per second at peak, but they also need to pause to look ahead and plan. Robots have no such limitation – they can compute the entire solution before starting and then execute it without interruption.

Another key difference is that humans must physically grip and rotate the cube, which introduces friction and the need to align faces precisely. Robots use precisely controlled motors that can turn a face in a fraction of a second without overshooting.

Common Misconceptions

One common misconception is that the robot is solving a scrambled cube from a random state. In fact, the robot is given a cube that is scrambled by a known sequence, and the software solves it from that state. The 0.637-second record was for a cube that had been scrambled by a random algorithm, but the robot still had to scan and solve it.

Another misconception is that the robot uses “brute force” – trying millions of moves. Actually, the solver uses a two-phase algorithm that finds a near-optimal solution in milliseconds. The 21 moves used is close to the theoretical minimum of 20, so the robot is not wasting time on extra turns.

Some people think the robot is cheating by using a cube with magnetic or lubricated internals. While the cube used was a standard speedcube (with magnets and lubricant), the same cube could be used by a human. The advantage is purely in the hardware and software, not in the cube itself.

Limits of the Record

The 0.637-second time is the fastest for a standard 3×3 cube, but it is not the fastest for any cube. Smaller cubes (like 2×2) can be solved faster because they have fewer pieces. There is also a category for “robot vs. human” races, but the official Guinness World Record for “fastest robot to solve a Rubik’s Cube” is currently 0.637 seconds (as of 2025).

The record could be broken by using faster motors, lighter arms, or a more efficient scanning system. However, there is a physical limit: the cube itself can only turn so fast before pieces fly off. The 0.637-second solve already approaches that limit, as the cube is subjected to forces of several Gs during the turns.

How to Build a Fast Solving Robot

If you want to build your own robot, the key components are:

• Stepper motors – they provide precise control and high torque. Servos are slower and less accurate.
• Camera and computer vision – a simple webcam with OpenCV can detect colors. You need to calibrate for lighting.
• Microcontroller or PC – a Raspberry Pi or Arduino can run the solver and control the motors.
• 3D-printed frame – the frame must hold the cube firmly and allow each face to be turned independently.

You can find open-source designs online, but building one that solves in under a second requires precise machining and high-speed electronics. Most hobby builds solve in 2–5 seconds.

Frequently Asked Questions

Is the 0.637-second solve officially recognized?

Yes, it was verified by Guinness World Records in 2018. The robot was built by MIT students Ben Katz and Jared Di Carlo, and the time was recorded on a standard 3×3 cube.

What is the fastest human solve?

As of 2025, the fastest human solve is 3.13 seconds, set by Max Park in 2023. The average world-class solver is around 5–6 seconds.

Why can’t a human solve as fast as a robot?

Humans need to physically rotate the cube with their fingers, which is limited by muscle speed and the need to visually track the cube. Robots use motors that can turn a face in 20 milliseconds, and they don’t need to look ahead.

Does the robot use a special cube?

It uses a standard speedcube, similar to what human cubers use, but with extra lubrication. The cube is not modified – the speed comes from the robot’s hardware and software.

Could a robot solve a cube in under 0.5 seconds?

Possibly, but it would require even faster motors and a more rigid frame. The main limit is the cube’s structural integrity – at very high speeds, the pieces can pop out. The current record is already near that limit.

How many moves does the robot use?

The robot’s solver typically finds solutions in 20–22 moves. The 0.637-second solve used 21 moves, which is close to the theoretical minimum of 20 for that scramble.

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in t | Solve time (seconds) | s | 0.637 | 0
out moves | Moves executed | - | 21 | 0
out tps | Effective turns per second | - | moves / t | 2