Learn the chase-the-lights method that solves every Lights Out puzzle, plus the full 5x5 bottom-row cheat sheet and quiet patterns for minimum moves.
Lights Out is the puzzle that looks like pure luck. You tap a square, five lights flip, three of them get worse, and ten minutes later you're clicking the same corner over and over wondering if the board is even solvable. It is — and there's a method that solves every valid board, every time, without guessing. This guide walks through that method step by step, gives you the complete bottom-row cheat sheet, and shows you how to trim your solution down to the minimum number of moves.
The version most people play is the classic 5×5 grid released by Tiger Electronics in 1995. Everything below is written for that board, and the same logic scales to other sizes with a few caveats I'll cover near the end. If you want to follow along, you can play Lights Out free on iQiQGame — it opens in a browser, no download.
The Rules, in Thirty Seconds
You get a 5×5 grid of lights, some on and some off. Pressing any cell toggles that cell and its four orthogonal neighbors — up, down, left, right. Diagonals are never touched. A corner press flips 3 lights, an edge press flips 4, a center press flips 5. The goal is to turn every light off.
That's the entire game. Which is exactly why it's maddening: every move you make to fix one light disturbs up to four others. Random clicking creates a light-shuffling loop that can go on forever, because — here's the key insight — the puzzle is not about sequences at all.
Two Facts That Change Everything
Before the method, internalize two properties of the board:
Fact 1: Pressing a button twice cancels out. A second press reverses the first press exactly. So a solution never presses the same cell twice — a solution is a set of cells, each pressed once.
Fact 2: Order doesn't matter. Press A then B lands the board in the same state as B then A. The board only cares about which cells end up pressed, not the order.
Together these two facts mean you can stop treating Lights Out as a sequence of moves to discover and start treating it as a question with a fixed answer: which subset of cells, pressed once each, clears the board? The math underneath is linear algebra over values that are either 0 or 1 — Marlow Anderson and Todd Feil proved in 1998 that any solvable 5×5 board has exactly four distinct solutions — but you don't need any of that machinery to play. The method below is the practical version of it.
Chase the Lights: The Core Method
The technique solvers call chasing the lights pushes every stray light downward until the whole board collapses. It works in two passes.
Pass 1 — sweep down. Look at the top row. For every light that's on, press the cell directly below it. That press toggles the lit cell off (it also toggles some cells in row 2, but you don't care yet). Move to row 2 and do the same: press below every lit cell. Repeat for rows 3 and 4. When you reach the bottom, rows 1 through 4 are completely dark — the only lights left are in row 5.
Pass 2 — read the bottom row. The pattern left in the bottom row is a fingerprint that tells you exactly which top-row cells to press. Use the cheat sheet below: find your bottom-row pattern, press the listed top-row cells, then sweep down one more time. The board goes dark.
That's it. Two sweeps and a lookup. It feels wrong the first time — Pass 2 turns lights back on in the upper rows on purpose — but the second sweep erases everything cleanly.
The 5×5 Bottom-Row Cheat Sheet
After your first sweep, only these eight bottom-row patterns can appear on a solvable board. Here is the verified mapping (columns labeled A–E, left to right):
| Bottom row lit cells | Press in top row |
|---|---|
| none — board already solved | nothing |
| A, B, C | B |
| B, D | B and E |
| A, C, D | E |
| A, E | A and B |
| B, C, E | A |
| A, B, D, E | C |
| C, D, E | D |
Three of the seven fixes are a single click. And if your bottom row shows a pattern not on this list — say, a single light, or lights only in D and E — the board is one of the rare unsolvable configurations, and no amount of clicking will clear it. Legitimate Lights Out games only deal solvable boards, so in practice this almost never happens; when it does, it means something got mis-clicked along the way.
A Worked Example
Take this board (# = on):
. . . # .
. # . . .
. # . # .
. . . # .
. # . . .
Sweep 1: row 1 has one lit cell at D, so press D2. Row 2 now has lights at B, C, D, E, so press B3, C3, D3, E3. Row 3's lights get answered with A4, B4, C4, D4. Nine presses in, rows 1–4 are dark and the bottom row reads A, C, D.
Lookup: A, C, D → press A1 and C1.
Sweep 2: chase down again, and the board clears completely. The full solution for this board uses 13 presses — and notice we never guessed, never repeated a cell, and never depended on luck.
Getting the Minimum Number of Moves
The chase method always solves the board but rarely in the fewest clicks, because the two sweeps can press the same cell twice (canceling) or take redundant detours. If you care about move counts — leaderboards do — you need one more idea: quiet patterns.
A quiet pattern is a set of top-row presses that, after a full sweep, changes nothing. On the 5×5 board there are exactly three non-empty ones:
. # # # . # . # . # # # . # #
# . # . # . # . # . # # . # #
# # . # # and . . . . . and . . . . .
# . # . # . # . # . # # . # #
. # # # . # . # . # # # . # #
Adding any quiet pattern to a valid solution gives you another valid solution — which is exactly why the Anderson–Feil count is four: the empty pattern plus these three. To minimize your move count, solve the board once with the chase method, then mentally XOR (add and cancel) each quiet pattern against your solution. One of the four combinations will be strictly shorter. Jaap Scherphuis's analysis of the classic board shows no 5×5 position ever needs more than 15 presses, so if your first solution came out at 20, a shorter one definitely exists.
In practice you don't do this every board. Do it when you're chasing a personal best; skip it when you're unwinding.
Common Mistakes That Keep People Stuck
Clicking randomly after the sweep stalls. The chase method doesn't stall. If things went sideways, you mis-pressed somewhere — the cleanest fix is to reset the board and run the method again from the top. Ten disciplined seconds beats a minute of hopeful clicking.
Forgetting what a press actually touches. Diagonals never flip. Corners flip 3, edges flip 4, centers flip 5. If you're predicting five flips from a corner press, your mental model is off, and the whole sweep breaks down.
Pressing the same cell twice in one sweep. It cancels out, which means you just wasted two clicks and likely mis-synced the rest of the sweep. If you catch yourself about to double-press, stop and re-read the row above.
Reading the bottom row wrong. The lookup only works on the exact fingerprint. "Roughly matches" isn't a thing here — A-C-D is not close enough to A-C-E. Double-check the pattern before pressing.
Giving up on an "unsolvable" board. Solvable boards always respond to the method. If yours doesn't, either a press went wrong mid-sweep or the board was generated badly. Reset, re-run, and it'll fall.
What About Other Board Sizes?
The chase method generalizes, but the lookup table doesn't transfer between sizes — each grid has its own bottom-row map, and some have quirks:
- 3×3 is always solvable and gentle — a great place to teach the method before betting a 5×5 streak on it.
- 4×4 "mini" variants often wrap around: the left and right edges are neighbors, so every press flips exactly 5 lights and chasing isn't possible. Check whether your version wraps before applying any of this.
- 6×6 is fully solvable for every starting pattern — no unsolvable boards at all.
- 9×9 chases like the 5×5, but occasionally leaves every other light on in the bottom row; pressing the top-left cell and chasing once more resolves it.
The underlying theory holds in every direction — mathematicians have shown that going from all lights on to all lights off is possible on any square grid, a result dating to Sutner's work in 1989 — but the practical takeaway is simple: re-derive or look up the table for whatever size you're playing.
Turn the Method Into Instinct
A method you've only read about fades fast. Here's a one-week drill that makes it permanent:
- Days 1–2: Solve five boards using the two-sweep method with the cheat sheet visible. Don't memorize yet — just prove to yourself it never fails.
- Days 3–4: Cover the table. Before each lookup, predict the fix, then check. The seven entries stick surprisingly fast.
- Days 5–7: After each solve, XOR one quiet pattern and see if your move count drops. Start aiming for sub-15 solutions on every board.
You can run the whole drill on the free Lights Out game at iQiQGame — each board takes a minute or two once the method clicks, and the discipline it builds (read the state, predict, verify) transfers directly to other logic puzzles like One Line path puzzles and Sudoku variants.
FAQ
Is every Lights Out puzzle solvable? No. On a 5×5 grid, only 1 in 4 random light patterns has a solution — but real games generate boards by pressing random cells from a solved state, which guarantees solvability.
Does the order of my clicks matter? No. Only the final set of pressed cells matters. Pressing a cell twice is the same as not pressing it.
What's the fewest moves possible on 5×5? It depends on the board, but no solvable 5×5 position needs more than 15 presses, and every solvable board has exactly four distinct solutions you can reach from one another by adding quiet patterns.
Why do I press top-row cells that turn lights back on? Those presses are a correction chosen so that the final sweep cancels every remaining light. It's the counterintuitive step that makes the method work — trust the table.
Can I use this method on the 4×4 wrap-around version? Not directly. Wrapping edges break the row-by-row chase. The math still applies, but you'd need that board's own solver table.
References
- Jaap Scherphuis, "Lights Out (Classic)" — chase solution, quiet patterns, and the 15-press bound: https://www.jaapsch.net/puzzles/lights.htm
- Marlow Anderson & Todd Feil, "Turning Lights Out with Linear Algebra," Mathematics Magazine 71(4), 1998 — proof that solvable 5×5 boards have exactly four solutions (summarized in the Wikipedia article below)
- Wolfram MathWorld, "Lights Out Puzzle" — the all-ones problem and Sutner's solvability result: https://mathworld.wolfram.com/LightsOutPuzzle.html
- Wikipedia, "Lights Out (game)" — game history, Tiger Electronics origins, and the Anderson–Feil analysis: https://en.wikipedia.org/wiki/Lights_Out_(game)
