Minesweeper Patterns: 1‑2‑1, 1‑2‑2‑1 and the Logic Behind Them

Minesweeper patterns are small arrangements of numbers that always lead to the same answer. Once you recognize them, you stop counting squares one by one and simply read the board: 1‑2‑1 means mines above the 1s, 1‑2‑2‑1 means mines above the 2s, and a 1‑1 from a wall clears the third square. This guide shows each pattern with a diagram and walks through exactly why it works.

If you are brand new to the game, start with how to play Minesweeper first.

How to read the diagrams

Every diagram below shows a small slice of a board where an open area meets a line of covered squares.

Legend
  a b c ...   covered squares (unknown)
  1 2 3 ...   revealed numbers
  ·           revealed square that does not matter here
  F           flagged mine
  │           edge of the board

In each diagram, the row of numbers sits directly under a row of covered squares, and everything below the numbers is already open. That means each number only "sees" the covered squares directly above it and diagonally above it.

Every pattern works in all four directions. Rotate or mirror the diagram and the logic is identical.

The idea behind every pattern

All Minesweeper patterns come from one simple comparison: two neighboring numbers share some covered squares. If you know how many mines can fit in the shared squares, you know how many mines must be in the squares that are not shared.

Keep that in mind and the patterns stop being things to memorize. They become shortcuts for a comparison you could do yourself.

The 1‑1 pattern from a wall

│ a  b  c
│ 1  1  ·
│ ·  ·  ·

1. The first 1 is against the wall. The only covered squares it touches are a and b. So there is exactly one mine in {a, b}.
2. The second 1 touches a, b and c. It also needs exactly one mine.
3. That one mine is already accounted for in {a, b}. So c has no mine.

Result: c is safe.

The "wall" does not have to be the edge of the board. Any time the first 1's other neighbors are already open or known, it works the same way. This is also why a 1‑1 in the middle of nowhere tells you nothing:

  p  a  b  c
  ·  1  1  ·
  ·  ·  ·  ·

Here the first 1 touches p, a and b. If the mine is on p, then a and b are safe and the second 1's mine must be c. If the mine is on a or b, then c is safe. Both are possible, so you cannot decide yet. Look for more information elsewhere.

Pro tip: After a 1‑1 clears a square, open it and check the new number. A 1‑1 against a wall often repeats all the way down the edge, clearing a square each time.

The 1‑2 pattern

  a  b  c  d
  ·  1  2  ·
  ·  ·  ·  ·

1. The 1 touches a, b and c, and holds exactly one mine. So the two shared squares b and c hold at most one mine.
2. The 2 touches b, c and d, and needs two mines.
3. At most one of those can come from b and c. So the other one must be d.
4. Now the 2 needs exactly one more mine, and it must be in b or c. That is also the 1's mine, so a is safe.

Result: d is a mine and a is safe. (Exactly one of b and c is a mine, but you cannot tell which yet.)

The short version players use: a 1 next to a 2 along a straight edge means the square on the far side of the 2 is a mine.

The 1‑2‑1 pattern

  p  a  b  c  q
  ·  1  2  1  ·
  ·  ·  ·  ·  ·

This is the most famous Minesweeper pattern, and it is just the 1‑2 pattern applied from both sides.

1. Look at the left 1 and the 2. They share a and b, which can hold at most one mine (because of the 1). So the 2's other square, c, must be a mine.
2. Now look at the right 1 and the 2. They share b and c, which can hold at most one mine. So the 2's other square, a, must be a mine.
3. The 2 is now satisfied by a and c, so b is safe.
4. The left 1 is satisfied by a, so p is safe. The right 1 is satisfied by c, so q is safe.

Result: a and c are mines. p, b and q are safe.

Easy way to remember it: 1‑2‑1, the mines sit over the 1s.

The 1‑2‑2‑1 pattern

  p  a  b  c  d  q
  ·  1  2  2  1  ·
  ·  ·  ·  ·  ·  ·

1. Left 1 and first 2: they share a and b, which hold at most one mine. So the first 2's other square, c, is a mine.
2. Right 1 and second 2: they share c and d, which hold at most one mine. So the second 2's other square, b, is a mine.
3. The first 2 touches a, b and c. With b and c both mines it is satisfied, so a is safe. By the same logic, d is safe.
4. The left 1 is satisfied by b, so p is safe. The right 1 is satisfied by c, so q is safe.

Result: b and c are mines. p, a, d and q are safe.

Easy way to remember it: 1‑2‑2‑1, the mines sit over the 2s.

Reduction: turning unfamiliar numbers into familiar patterns

Real boards rarely show a perfect 1‑2‑1. More often you see bigger numbers that are touching mines you already know about. Reduction means subtracting those known mines so you can see the pattern hiding underneath.

  p  a  b  c  q
  ·  2  3  2  ·
  ·  ·  F  ·  ·

The flagged mine F sits below the 3 and touches all three numbers (it is diagonal to both 2s). Subtract it from each of them:

For the covered squares, the row now behaves exactly like 1‑2‑1. So a and c are mines, and p, b and q are safe.

Reduction works with any known mine, flagged or not. Train yourself to ask "how many mines does this number still need?" instead of "what number is this?" and you will find patterns everywhere.

Pro tip: Only subtract mines you are certain of. A wrong flag makes every reduction around it wrong too, and chording on a wrong flag ends the game.

Numbers that solve themselves

Before hunting for patterns, clear the two easy cases:

• A number equal to its covered neighbors. If a 3 touches exactly three covered squares, all three are mines.
• A satisfied number. If a number already touches as many known mines as it shows, every other covered square around it is safe. On Poozee you can click that number to chord and open them all at once.

These two checks, plus the patterns above, solve the large majority of what you will see on Beginner and Intermediate boards.

Playing faster: flags, chords and order

Patterns make you accurate. A few habits make you fast:

1. Work along one edge at a time. Patterns chain. Clearing a square with a 1‑1 often creates the next 1‑2 right beside it.
2. Flag only when it helps. Flags are for chording and for keeping track. On an easy edge, opening the safe squares directly is quicker than flagging first.
3. Chord whenever a number is satisfied. One click instead of three or four.
4. Save the hard spots for later. When an area stalls, move to another edge. New numbers elsewhere often solve the stuck spot.

When patterns run out: 50/50s

Sometimes there is truly no logical answer. The classic example is two covered squares where one is a mine, and every number around them treats them the same. No pattern can split them, so you have to guess. Our guide to Minesweeper 50/50s measures how often each level forces a guess and how to pick the safest square.

Two tips for when that happens:

• Guess early. If a 50/50 is unavoidable, take it before you spend five minutes clearing the rest of the board.
• Count mines at the end. Near the end of a game, the mine counter can break a tie. If only one mine is left and it must be in one of two squares, anything else still covered is safe.

Keep playing

The best way to learn patterns is to see them in real boards. Open a game of Minesweeper on Beginner, find one 1‑2‑1 or 1‑1 before every click, then step up to Intermediate once it feels automatic. If you enjoy this kind of logic, Sudoku strategies use the same "what can fit here?" thinking, and so does our guide on how to solve nonograms.