This guide shows you how to solve a 4x4 Rubik’s Cube, also known as the Rubik’s Revenge, with the reduction method. The idea is simple: you group the small pieces of the 4x4 into big blocks until it behaves exactly like a 3x3. First you build the six centers, then you pair up the edges, and then you solve it with the 3x3 method you already know. Two special cases, called parities, can appear at the end; each one has its own algorithm, and both are explained below with 3D demonstrations.
You should be able to solve a 3x3 before you start. If you cannot yet, learn the 3x3 beginner method first: step 3 of this guide is that whole method.
Before you start
Know the pieces. A 4x4 has 8 corners, just like a 3x3. It has 24 edge pieces, two on each of the 12 edges of the cube; we call two matching edge pieces a pair. It has 24 center pieces, four on each face. Unlike the 3x3, the centers are not fixed: they move when you turn an inner layer, so there is no center piece that tells you which color a face should be. You decide that yourself while you build the centers.
Learn the extra notation. Outer turns use the same letters as the 3x3: R, L, U, D, F, B, with ′ for counter-clockwise and 2 for a half turn. The 4x4 adds two kinds of moves:
- Rw (a “wide” turn) turns the two right layers together, like holding the outer and the inner layer as one. Uw, Lw and the others work the same way.
- 2R turns only the second layer from the right, the inner slice, without the outer face. 2U, 2L and the others work the same way.
Some guides write the inner slice as a lowercase r, while others use a lowercase r for the wide turn. To avoid the confusion, this guide always writes Rw for the wide turn and 2R for the inner slice. The notation guide shows the outer moves in 3D.
Use the standard color scheme. Because the centers can go anywhere, you must place them in the same arrangement as on a solved cube: white opposite yellow, blue opposite green, red opposite orange. If you look at the top of a solved cube with white on top and green in front, red is on the right. Check a corner piece if you are unsure: the white, green and red corner tells you that red must be to the right of green when white is on top.
Plan for a long first solve. Your first 4x4 solve with a guide can take one or two hours. That is normal. By the third or fourth solve most people finish in 10 to 15 minutes.
Step 1: Solve the centers
The first goal is six solid centers: each face gets a 2x2 block of four center pieces of one color, arranged in the standard color scheme. Corners and edges do not matter yet.
White center. Pick up the cube and find white center pieces. Build a 1x2 bar of two white center pieces on one face, then a second bar, and join the two bars into a 2x2 block. You can do this intuitively with inner-slice turns: bring a white piece to the face you are building, turn that face so the piece lines up next to the one you already have, then use a slice move to bring it in. Take your time; it is the step that needs the most thinking.
Yellow center. Turn the cube so white is on the bottom and build the yellow center on top. Now the bottom must not be broken again, so only use wide turns such as Rw and Rw′ that you undo right away, and turns of the top layer.
The last four centers. These go around the middle: blue, red, green and orange, in the right order. Build each one from two 1x2 bars. The main trick is the insertion move: with a bar on the top face lined up above the front face, do Rw U Rw′ (or its mirror) to bring pieces from the front up and back again, changing which pieces are in front. Look at what each move does to the top face and to the front face; three moves only swap the bars you want to swap.
Rw U Rw′
The demonstration finishes the last two centers. At the start the top and front faces each have one bar of the wrong color; after the moves both are solid. The outer turns at the end show that the centers stay solved while other pieces move.
Before you continue, check the color scheme: with white on the bottom and yellow on top, the side centers must go blue, red, green, orange in one direction around the cube, exactly as on a solved 3x3. If two neighbouring side centers are swapped, the cube cannot be solved; fix it now by swapping them.
Step 2: Pair the edges
Now pair up the 24 edge pieces into 12 complete edges. When an edge is paired, both of its pieces show the same two colors side by side, and it behaves like a single 3x3 edge from then on.
Keep the centers in mind: you may turn inner layers, but you must always undo them before you start the next pair. The method below does that automatically. It is often called slice, flip, slice:
- Hold the cube with white on the bottom. Find two pieces of the same edge, for example the two white-red edge pieces.
- Put one of them in the middle layer at the front left and the other in the middle layer at the front right, with the same colors facing you. Do this with outer turns only, so the centers stay solid.
- Look at their heights. The piece on the left must be in the upper inner row and the piece on the right in the lower inner row of the middle, or the other way round, so that turning the upper inner layers (Uw′) brings them together on one side.
- Do the algorithm below. Uw′ joins the two pieces into a pair; R U R′ F R′ F′ R moves that finished pair to the top and brings in an unpaired edge in its place; Uw puts the centers back.
Uw′ R U R′ F R′ F′ R Uw
Repeat for each edge. The first eight edges are easy because there is plenty of room to set up the pieces. For the last two or three edges you may need the algorithm once more to swap an unpaired piece into position. Keep the finished pairs in the top and bottom layers; the algorithm only uses the right-hand side for storage.
The demonstration pairs one edge and puts the centers back, then shows that outer turns keep every pair together. When all twelve edges are paired and the six centers are still solid, the 4x4 has been reduced to a 3x3.
Step 3: Solve it like a 3x3
From now on, treat each 2x2 center as a single center, each pair as a single edge, and only turn outer layers (R, U, F, L, D, B). The inner layers must not move, or you will break the centers and pairs you just built.
Solve the cube with the 3x3 beginner method:
- White cross on the bottom, with each edge matching its side center.
- White corners.
- Middle-layer edges.
- Yellow cross on top, with F R U R′ U′ F′.
- Yellow edges matched to the side centers.
- Yellow corners in place.
- Yellow corners twisted.
Every algorithm from the 3x3 guide works unchanged, because outer turns on a 4x4 move the paired edges and the centers exactly like on a 3x3. The demonstration uses the yellow cross algorithm on the 4x4.
About half of your solves will finish without any trouble. In the other half, one of two situations appears that can never happen on a 3x3. They are called parity, and they are not your mistake: they come from how the edges were paired, and you cannot see them coming. The next two steps fix them.
Step 4: Fix OLL parity (one flipped edge)
How to recognize it. You are making the yellow cross on top and you end up with an odd number of yellow edges facing up: one or three instead of zero, two or four. On a 3x3 that is impossible. On the 4x4 it means one edge on top is flipped the wrong way round.
How to fix it. Hold the cube so the flipped edge is at the front of the top layer (yellow sticker facing you), and do this algorithm:
2R2 B2 U2 2L U2 2R′ U2 2R U2 F2 2R F2 2L′ B2 2R2
It is long, but it has a rhythm: inner slice, two half turns, inner slice. Practise it slowly, and pay attention to the difference between the inner slices (2R, 2L) and the outer half turns (B2, U2, F2). The algorithm flips the front top edge in place and leaves the rest of the cube as it was, including the first two layers.
After the algorithm you will have an even number of yellow edges facing up, and you can continue with the normal yellow cross from step 4 of the 3x3 method.
The demonstration starts from a cube that is solved except for one flipped edge on top, and fixes it.
Step 5: Fix PLL parity (two swapped edges)
How to recognize it. The top is fully yellow, but at the end two edges of the top layer are swapped with each other, or two corners appear swapped, which no 3x3 algorithm can solve. The most common version: everything matches except the front and back top edges, which have traded places.
How to fix it. Turn the top layer so the two swapped edges are at the front and back of the top, then do:
2R2 U2 2R2 Uw2 2R2 2U2
The algorithm swaps the front and back top edges. It is short: three inner-slice half turns, one outer half turn and two half turns of the upper layers. If the parity shows up differently, for example as two corners that seem swapped, do this algorithm once anyway and then go back to step 5 of the 3x3 method: the case has turned into one the normal 3x3 steps can finish.
The demonstration starts from a cube that is solved except for two swapped top edges.
After this step the 4x4 is solved. Congratulations: you can now solve both the 3x3 and the 4x4, and the same reduction idea works for the 5x5 and bigger cubes.
Common problems
The centers get broken while pairing edges. Every inner-layer turn must be undone before you move on. In the slice, flip, slice algorithm the first Uw′ and the last Uw cancel each other; if you forget the last Uw, the side centers stay shifted.
A pair falls apart in step 3. You turned an inner layer by mistake, often while doing a wide turn out of habit. Check that you only use outer turns in step 3.
The cube cannot be solved at the end. Check the center colors: if two side centers were placed in the wrong order in step 1, no algorithm can fix it. Start again from the centers.
What to practise next
Once you can solve the 4x4 with this guide, time yourself with the cube timer and try to get under five minutes. Most time goes into edge pairing, so that is where practice pays off. Faster solvers pair edges several at a time and learn shorter parity algorithms, but the reduction method stays the same all the way up to the 7x7.