Minesweeper Patterns Cheat Sheet
Each number on a Minesweeper board counts the mines in the eight squares around it. A pattern is a group of numbers that forces the same answer every time you see it, so once you know it you can click without working it out again. Below are the patterns that come up most, each with a board and the reason it works. Open Mine Field in another tab and look for them as you read.
Every wall diagram uses the same setup: the numbers sit in one row, the row above them is unopened, and everything below them is already open. Letters name the unopened squares. M marks a mine, S marks a safe square, and ? means the pattern alone does not decide it.
Start with reduction
Subtract any flagged mines a number already touches. A 3 with one flag next to it needs two more mines among its other unopened neighbours, so treat it as a 2. Most hard-looking spots turn into one of the patterns below once you do this. There is a worked example further down.
1-2-1
Board
Answer, top row
The 2 touches b, c and d and needs two mines there. The left 1 touches a, b and c, so b and c together hold at most one mine. The 2 has to find its other mine in d. The same reasoning from the right 1 puts a mine in b. With b and d both mines, the 2 is full and c is safe. Each 1 is full as well, which clears a and e.
Short version: in 1-2-1, the mines sit above the 1s.
1-2-2-1
Board
Answer, top row
The left 1 allows at most one mine in b and c, and the left 2 touches b, c and d, so d is a mine. The right 1 and right 2 force c the same way. Each 1 now touches one mine (c for the left 1, d for the right 1), so a, b, e and f are all safe.
Short version: in 1-2-2-1, the mines sit above the 2s.
2-1-2
Board
Answer, top row
The 1 touches b, c and d and holds exactly one mine there. The left 2 touches a, b and c. Only one of b and c can be a mine, so a must be one. The right 2 forces e the same way. If the 1's mine were in b, the right 2 would need a mine in c or d as well, and the 1 would see two. A mine in d fails the same way from the left. That leaves c as the mine, with b and d safe.
1-1 from the edge
Board
Answer, top row
The first 1 sits against the side of the board, so its only unopened neighbours are a and b. The second 1 touches a, b and c. The mine the first 1 needs is in a or b, and that same mine satisfies the second 1, so c is safe. This only works when the row of 1s starts at the edge, or at an opened square that closes off that side.
1-2: the square past the 2 is a mine
Board
Answer, top row
The 1 touches a, b and c. The 2 touches b, c and d. The 1 allows at most one mine in b and c, so the 2 needs d. The 2 still needs one more mine in b or c, and that mine is also the 1's only mine, which makes a safe. Players often write this as 1-2-X: X, the square past the 2, is a mine.
Reduction in practice: 2-3-2 becomes 1-2-1
Board
Answer, top row
The flag below the 3 touches all three numbers. Take one away from each and the row reads 1-2-1. b and d are mines, and a, c and e are safe. The same move turns 2-3-3-2 into 1-2-2-1 when flags bring each of those numbers down by one.
Cheat sheet
| Numbers | Where | Mines | Safe |
|---|---|---|---|
1-2-1 | Flat wall | Above each 1 | Above the 2, and one square past each 1 |
1-2-2-1 | Flat wall | Above each 2 | Above each 1, and one square past each 1 |
2-1-2 | Flat wall | Above the 1, and one square past each 2 | Above each 2 |
1-1 | Starting at an edge | One of the first two squares | Third square |
1-2 | Flat wall | Square past the 2 | Square before the 1 |
2-3-2 with a shared flag | Flat wall | Subtract the flag and solve as 1-2-1 | |
Chording saves clicks
Once a number touches as many flags as its value, you can open all of its other neighbours at once. On desktop versions you usually click both mouse buttons together or middle-click the number. In Mine Field you tap the number. Press and hold an unopened square, or switch to Flag mode, to place a flag.
Speed players rate a board by its 3BV, the smallest number of left clicks that clears it without flags. A chord can open several squares in one click, which is how fast players finish in fewer clicks than a flag-free solve would take.
A chord trusts your flags. If one flag is wrong, the chord opens the real mine and the game ends. Mine Field refuses a chord until the flag count matches the number, but it cannot check that the flags are in the right places.
When you have to guess
Classic Minesweeper places mines at random, so some boards cannot be finished by logic alone. The usual case is two unopened squares side by side against an edge, where every number nearby touches both of them or neither. Either square could be the mine, and no amount of logic separates them.
- Finish the rest of the board first. New numbers, and the mine counter near the end, can settle a spot that looked like a guess.
- Use the counter. If one mine is left and one unsolved area must contain it, every other unopened square is clear.
- Compare odds. A 50/50 square is a mine half the time. An unopened square far from any number is a mine roughly as often as the mines left divided by the unopened squares left, which is often much lower.
- If you must guess next to numbers, pick a square that will give you a useful number if it is safe, not one tucked into a corner that tells you nothing new.
Mine Field makes your first tap safe, so you never lose on the opening click.