How to use the 4x4 solver
This 4x4 solver works from the colors of your own Rubik's Revenge style cube. A 4x4 has no fixed center pieces, so hold it any way you like, but keep that same grip while you enter the colors and while you follow the moves.
- Pick a color in the palette and tap the stickers that have it, on the flat net or on the 3D cube. Each color needs exactly 16 stickers; the counters show your progress.
- Fill all six faces. If you are unsure how a face lines up with the others, open I can only see two or three faces under the Solve button.
- Press Solve. The solution appears in stages; tap a stage to jump to it, or press play and follow the arrow on the 3D cube.
Have a scramble written down? Choose Type a scramble and paste it. It reads outer turns (R, U'), wide turns (Rw or r), inner slices (2R) and whole-cube turns (x, y, z).
Reading 4x4 moves
A plain letter turns only the outer layer of that face: R is the right face a quarter turn clockwise as you look at it. A w means a wide turn: Rw turns the two right-hand layers together, as one block. An apostrophe means counter-clockwise and a 2 means a half turn. 2R2 turns only the second layer from the right, a half turn; it appears only in the parity fix.
How the 4x4 Rubik's cube solver works
The solver uses reduction, the same plan most people learn: turn the 4x4 into a big 3x3, then solve that.
- Centers. First white and yellow centers go to the top and bottom, then red and orange to the sides, then every center is finished. Each step reads an exact distance table, so each one takes the fewest moves its turn set allows.
- Edge pairing. Each edge of a 4x4 is two separate pieces. The solver joins them by opening a wide layer, swapping pieces with a short trigger like R U R', and closing the layer again, so the centers end where they were. It searches many orders at once and keeps the shortest.
- 3x3 stage. With centers and edges done, the cube turns like a 3x3 and a two-phase 3x3 solver (the same one our Rubik's cube solver uses) finishes it in 22 moves or fewer.
Parity on a 4x4
Two problems can appear on a 4x4 that a 3x3 never shows. OLL parity is a single edge that looks flipped; this solver removes it while it solves the centers, so it never needs the long OLL parity algorithm. PLL parity is two edges that need swapping; when the pairing search cannot avoid it, the solver adds a 6-move fix (2R2 U2 2R2 Uw2 2R2 Uw2) before the 3x3 stage, labeled as its own stage.
How long the solutions are
In our test of 300 random cubes, solutions averaged 70 moves, with the shortest at 59 and the longest at 83, counting every turn of one layer or two layers together as one move. That is far shorter than a beginner method, though longer than the best possible solution, which no practical solver can find for a 4x4. Every solution is replayed on two separate cube models before it is shown.
A worked example
Type the scramble Rw U2 Fw' R2 Uw D' L2 Fw2 U' Rw2 B L' Uw2 F2 Rw' D B2 Uw R' F and press Solve. You get 67 moves: 19 for the centers, 26 to pair the edges and 22 for the 3x3 stage. This scramble has OLL parity, which the center stage removes, and no PLL parity.
Tips
- Check the centers first if the solver says a color count is wrong: each color has exactly 4 center squares.
- Keep your grip. Every move assumes the cube has not been turned over in your hands.
- Go slowly through the edge stage; a missed wide turn is the most common slip.
To learn the method by hand, read how to solve a 4x4 Rubik's cube: centers first, then edge pairs, then the 3x3 stage and its parity cases.
Solver tested . Found a problem? Tell us.
Questions
Is this 4x4 solver free?
Yes. It is free with no sign-up and no download. It runs in your browser, and the colors you enter are not sent anywhere.
Why does my 4x4 cube show one flipped edge at the end?
That is OLL parity, which can happen on any 4x4 because its centers and edges are made of separate pieces. If you follow this solver's moves from your scrambled cube, it removes OLL parity during the centers stage, so you will not see it.
What is PLL parity on a 4x4?
PLL parity is when two edges (or two corners) need to swap at the very end, which a 3x3 can never do. The solver fixes it with the 6-move sequence 2R2 U2 2R2 Uw2 2R2 Uw2 before the last stage when it is needed.
Which way should I hold the cube?
Any way you like, as long as you keep the same grip while you enter the colors and while you follow the moves. The solver never asks you to turn the whole cube. When it finishes, the colors of the corner at the bottom, back and left decide which color ends on each face.
Can it solve a Rubik's Revenge or any 4x4 speed cube?
Yes. Any 4x4 cube with the standard color scheme works: white opposite yellow, green opposite blue and red opposite orange.
Why does it say my cube cannot be solved?
Usually one or two stickers were entered in the wrong place. The message names the problem, such as a twisted corner or two identical edge pieces, and outlines the stickers to check. A corner that really was twisted by hand has to be twisted back before the cube can be solved.