In the world of cubing, “God’s Number” refers to the absolute maximum number of moves required to solve any possible scramble of a 3x3 Rubik’s Cube. It assumes the solver possesses “God’s Algorithm”—the ability to instantly see the most mathematically perfect, shortest path to a solved cube.
For decades, mathematicians debated what this ultimate number could be. Today, we know the answer: 20 moves.
But how did we get there, and what does it mean for a beginner just trying to solve their first cube?
The 30-Year Mathematical Quest
The Rubik’s Cube has roughly 43 quintillion (43,252,003,274,489,856,000) possible combinations. Checking every single one manually is impossible.
Over the years, mathematicians slowly chipped away at the puzzle. In 1995, mathematician Michael Reid proved that a specific pattern required exactly 20 moves, meaning God’s Number couldn’t be any lower than 20. Over the next 15 years, researchers used clever math to lower the “maximum” possible moves from 28, down to 26, then 22.
Finally, in 2010, a team of researchers (Tomas Rokicki, Herbert Kociemba, Morley Davidson, and John Dethridge) teamed up to end the debate. By borrowing idle time on Google’s massive server infrastructure, they crunched the numbers using the equivalent of decades of CPU processing time.
They successfully proved that every single position is solvable in at most 20 moves.
What Counts as a “Move”? (HTM vs. QTM)
To understand God’s Number, you have to know how mathematicians count moves.
The 20-move rule uses the Half-Turn Metric (HTM). In HTM, twisting a face of the cube counts as exactly one move, regardless of whether you turn it 90 degrees (a quarter turn) or 180 degrees (a half turn).
Fun Fact: If you use the Quarter-Turn Metric (QTM)—where a 180-degree turn counts as two moves—God’s Number actually jumps up to 26!
The Infamous “Superflip”
You might assume that the hardest scrambles are the ones that look the messiest. Surprisingly, that isn’t always true!
One of the most famous positions that requires the absolute maximum of 20 moves is called the Superflip. In this state, all 8 corners are perfectly solved, and all 12 edges are in the correct spots—but every single edge is flipped “inside-out.”
It is a beautiful, highly symmetrical pattern, but because of the way the cube’s mechanics work, it requires a mathematically grueling 20 moves to fix. Out of the 43 quintillion possibilities, only about 300 million positions actually require the full 20 moves.
Why Humans Don’t Use God’s Algorithm
If a computer can solve a cube in 20 moves, why do human beginners take over 200 moves, and even professional speedcubers take 50 to 60 moves?
The answer is simple: God’s Algorithm is completely non-intuitive.
A 20-move computer solution doesn’t build a cross, it doesn’t solve one layer at a time, and it doesn’t use recognizable patterns. It relies on chaotic, abstract moves that no human brain could possibly memorize or calculate on the fly. Speedcubers use methods like CFOP, and beginners use Layer-by-Layer (LBL), because they rely on chunking the cube into bite-sized, logical steps and muscle memory.
Leave the 20-Move Solves to the Computers
Don’t stress if your solve takes 100 or 200 moves! That means you are learning the cube the human way.
Instead of trying to calculate billions of possibilities in your head, let our CubeUnstuck Digital Tutor help you. Using your webcam, it digitizes your physical cube and teaches you the beginner-friendly Layer-by-Layer method step-by-step.
Read more about solver to stop worrying about the math and start enjoying the solve!