Cube Notation

Every move is a letter naming a face of the cube. The cube stays visible behind this guide — press Try on anything to watch it happen.

The six faces

U F R

The hidden sides are their opposites: L left, B back, D down. Faces are named from your point of view — whichever side faces you is F.

UUp (top)
DDown (bottom)
LLeft
RRight
FFront
BBack

Three ways to turn a face

Clockwise means as if you were looking straight at that face. So B turns the opposite way from F when seen from the front — try both!

The same three forms work on every face. All 18 possible face turns — click any to watch:

Reading a sequence

Algorithms read left to right, one move at a time. The most famous one, the “sexy move”:

RUR'U'

Repeat it six times from a solved cube and everything returns to where it started. Undo works on tried moves, so experiment freely.

Advanced: slices, rotations, wide turns

Three more families of moves — and the ' and 2 modifiers work on all of them too (M', x2, r' …).

Slice moves — just the middle layer

MMiddle — between L and R, follows L
EEquator — between U and D, follows D
SStanding — between F and B, follows F

Rotations — turn the whole cube in hand

xWhole cube, same way as R
yWhole cube, same way as U
zWhole cube, same way as F

No stickers change place relative to each other — a rotated solved cube is still solved.

Wide turns — two layers at once

A lowercase face letter turns that face plus the slice next to it. Also written with a w: r = Rw.

uUp (Uw)
dDown (Dw)
lLeft (Lw)
rRight (Rw)
fFront (Fw)
bBack (Bw)

Bigger cubes: numbered layers

On 4×4 and up, a number in front picks how deep. A bare number turns just that one inner layer; with a w it turns that many outer layers together. (Buttons grey out if the move doesn’t exist on the current cube size.)

2ROnly the 2nd layer in from R
3UOnly the 3rd layer down from U
3RwThe three outermost layers from R, together
4FwThe four outermost layers from F, together

Slice moves M E S exist only on odd sizes (3, 5, 7) — even cubes have no middle layer. Rotations x y z work on every size.

God’s Number

Every position of the Rubik’s Cube — all 43,252,003,274,489,856,000 of them — can be solved in 20 moves or fewer. That worst-case number is called God’s Number: the number of moves an all-knowing solver would ever need.

What exactly is it?

For any scramble there is some shortest possible solution. God’s Number is the longest of all those shortest solutions — the diameter of the cube’s universe. In the half-turn metric (where R and R2 each count as one move) it is exactly 20; in the quarter-turn metric it is 26.

The hardest position

The superflip — every piece in place, every edge flipped — was proven in 1995 to require the full 20 moves. It looks like this (works on the 3×3):

superflip

How the answer was found

1981≤ 52Thistlethwaite’s nested-group algorithm
1995≤ 29Reid — and proves the superflip needs 20
1992–2008≤ 22Kociemba’s two-phase idea, refined by Rokicki
2010= 20Rokicki, Kociemba, Davidson & Dethridge — about 35 CPU-years donated by Google checked every position

What this app uses

Knowing 20 is enough doesn’t make it fast to find a 20-move solution — truly optimal solving still takes a long search per scramble. The Kociemba tab here uses his two-phase algorithm: it first maneuvers the cube into a friendly subgroup, then finishes it, giving ~19–23 move solutions in milliseconds. Short, but not guaranteed shortest.

The 2×2 is small enough to search exhaustively: its God’s Number is 11, and the Optimal tab really does return a shortest-possible solution.