Rubik's Cube Solver

How to read your cube into the solver

Pick a colour, then tap the squares that show it. Hold the cube with one face toward you: that is Front, and whatever points at the ceiling is Up. To see the Right, Left or Back, turn the whole cube on the table so that face comes round to you, keeping Up on top. For Up, tip the cube toward you; for Down, tip it away. Paint each face exactly as it looks from there, centres included.

Every colour appears on exactly nine squares, and the counter above the net turns red until it does. The centres never move on a real cube, so they tell the solver which colour belongs on which face; any colour scheme works.

What the moves mean

Moves use the standard letters for each face: R Right, L Left, U Up, D Down, F Front and B Back. A plain letter is a quarter turn clockwise as you look straight at that face. A letter with a dash, R', is a quarter turn anticlockwise, and R2 is a half turn. The face to turn next is outlined on the net, and Step walks the solution one move at a time with the net updating as it goes.

When it says your cube cannot be right

A painted net that no real cube could show is nearly always one of three slips, and the solver says which. A twisted corner is a corner with its three colours in the wrong order. A flipped edge is an edge with its two colours the wrong way round. And two swapped pieces is the one a real cube cannot do at all unless it has been taken apart and put back, so it usually means two squares painted in each other's place.

If a check comes back clean and the cube in your hands still will not solve, the cube itself has been reassembled or had a sticker moved. That is worth knowing before spending an evening on it.

How it works

It uses Herbert Kociemba's two-phase method: first bring the cube into a state that only needs half turns on four of its faces, then finish with those. That is what lets it search 43,252,003,274,489,856,000 positions in a fraction of a second. Its answers come out at around 22 moves. The shortest possible is never more than 20, which is God's number, proved in 2010; a solver that guaranteed 20 every time would take far longer for two moves' saving.

It was tested before it went up: hundreds of random scrambles, every one solved in 24 moves or fewer, and every kind of painting slip caught and named.

More on the Rubik's Cube

Why there are 43 quintillion positions and how God's number was found are in the mathematics of the Rubik's Cube. Two of its cousins have solvers here too: the Void Cube, which has no centres, and the Gear Cube, which only turns in half turns.

We do not make twisty puzzles. If what you enjoyed was the sequence rather than the colours, the closest things we make are the Snake Cube, where 27 blocks on a cord can only be wrong in their order, and EcstaTIC, a two-piece cube that needs a rotation almost nobody tries. There are more solvers on the puzzle tools page.