Minesweeper patterns: how to clear a board without guessing

What a number tells you

A number on an opened square counts the mines in the squares that touch it: the four beside it and the four on its diagonals. A 1 in open ground has eight neighbours and one mine among them; a 1 against a wall has only five neighbours, and a 1 in a corner only three. The fewer covered squares a number touches, the more it gives away.

Two simple rules do most of the work:

• Subtract correctly flagged mines first. If the remaining mine count equals the number of covered, unflagged neighbours, all of those neighbours are mines. A 2 with no flags and two covered neighbours needs a mine in each; a 2 with one justified flag and one remaining covered neighbour needs one more mine.
• When justified flags satisfy a clue, its other covered neighbours are safe. A 1 next to a correctly identified mine needs nothing more. An arbitrary flag is not proof that the mine is there.

Everything below is these two rules, applied to two or three numbers at once.

How to read the diagrams

Each diagram shows a strip of the board: the bottom row is opened squares and the top row the covered squares beyond them. The illustrated numbered clues have no other unresolved covered neighbours. A square further away matters whenever it also touches one of those clues; do not ignore it simply because the same number pattern appears nearby.

• 1, 2 — an opened number; . — an opened square whose number does not matter here
• * — certainly a mine: flag it
• o — certainly safe: open it
• a — exactly one of the squares marked a is a mine, you cannot yet tell which
• | — the wall at the edge of the board

The 1-1 pattern along a wall

Picture a straight edge of opened squares, with covered squares beyond it, and two 1s side by side on that edge. The first 1 touches three covered squares; the second touches the same three, shifted along by one.

If the first 1 sits at the end of the row — against a wall or a corner — it only touches two covered squares, and the mine must be in one of them. Both of those squares also touch the second 1. That second 1 has now used up its one mine, so the covered square it touches beyond the first two is safe. Open it.

| a a o
| 1 1 .

This is the most common deduction in the game. Whenever you see a 1 at the end of an edge, look at the number next to it.

The 1-2 pattern

Now take a 1 and a 2 side by side on an edge. The 2 touches three covered squares; the 1 touches two of those same three.

The 1 can account for at most one mine among the squares the two numbers share. The 2 needs two mines, so its other one must be in the square only the 2 touches. Flag it. If the 1 touches a square the 2 does not, that square is safe, because the 1's mine is already among the shared ones.

o a a *
. 1 2 .

Read it as: the bigger number needs mines the smaller one cannot give it.

1-2-1 and 1-2-2-1

For the straight strip shown below, 1-2-1 forces mines under the two 1s and a safe square under the 2. This depends on all other neighbours of those clues already being known safe, or having justified flags subtracted from the clues. Work from each end and both 1s point to the same result. The squares just beyond the two 1s are safe too, because each 1 already has its mine.

o * o * o
. 1 2 1 .

With the same boundary conditions, 1-2-2-1 is its longer cousin: the mines are under the two 2s, and the squares under the 1s are safe. If extra covered neighbours remain, return to the constraints rather than copying this result.

o o * * o o
. 1 2 2 1 .

These two are worth memorising as shapes. Spotting them takes a glance, and on a 12×12 board they turn up again and again.

2-1-2

The 1 in the middle allows only one mine among the three squares it touches. Each 2 needs two mines, and at most one of them can be shared with the 1 — so each 2 has a mine in the square at its far end. Both 2s still need their second mine from the squares they share with the 1, and since the 1 allows only one mine across all three, it must be the square both 2s share: the one under the 1. So the mines are at the two ends and under the 1, and the squares under the 2s are safe.

* o * o *
. 2 1 2 .

Work through a 1-2-1 before you flag

The illustration below shows the conclusion, rather than a board to copy blindly. The three numbered cells are already open. Only the five cells immediately above them are covered; all other neighbours of the clues are known to be safe.

1. The middle 2 needs two mines among its three covered neighbours.
2. If the middle covered cell were a mine, either extra mine beside it would make one of the end 1s touch two mines. That is impossible, so the middle cell is safe.
3. The two remaining neighbours of the 2 must both be mines. Flag those two cells.
4. Each end 1 now has its one mine accounted for, so the covered cells at the far ends are safe too.

The longer edge works the same way. In a 1-2-2-1, the two central covered cells are mines and the four outer cells shown here are safe. Keep the same condition: there are no extra covered neighbours behind or beside the numbered row. At a bend or a partly covered second edge, use the numbers directly instead of applying a memorised shape.

Read the opening area in an actual game

Begin at a numbered edge, not at an isolated covered square. Count that clue's covered neighbours and any flags you can already justify. If the remaining mine count equals the remaining covered neighbours, all of those neighbours are mines. If the clue is already satisfied by correct flags, its other neighbours are safe. Then compare an adjacent clue to see whether their shared neighbours reveal another safe cell. The screenshot is an example opening; every dealt board is different.

Subtract the flags you already have

Most numbers on a real board do not sit in a clean row. The trick that turns a messy edge into one of the patterns above is to subtract the flags a number already touches. A 3 that touches one flag behaves exactly like a 2 for the squares still covered around it; a 2 that touches one flag is a 1.

Do that in your head along an edge: a 2-3-2 whose numbers each touch one flag is a 1-2-1 in disguise. Every pattern in this guide works on the reduced numbers.

Common mistakes

• Forcing a pattern that is not there. The diagrams only hold when the covered squares are all on one side of the row. If there are covered squares on the other side too, or the row bends, work the numbers out from the rules instead.
• Forgetting the squares at the ends. In a 1-2-1 the squares just beyond the 1s are safe; players who only open the square under the 2 leave easy squares behind.
• Flagging and moving on. A flag is worth most when you use it straight away: subtract it, or chord on the numbers around it.

Chording: opening many squares at once

When a number already touches as many flags as it shows, tap it. Mines opens every other covered square around it in one move. This is called chording, and it is the biggest single saving of time in the game: three taps become one.

Chording trusts your flags. If a flag is in the wrong place, chording around it opens a mine. Flags are notes you keep for yourself, and a wrong one only hurts when you chord next to it — so flag with care, and chord where you are sure.

Counting at the end

Near the end of a board the mine counter becomes a clue of its own. Mines shows how many mines are still unflagged; the solver that checks every board knows that total too, and so should you.

Say two mines are left and the covered squares form several separate pockets. If one pocket must hold at least one mine and the other must hold at least one, each holds exactly one — and any third pocket is entirely safe. Counting like this settles the last few squares that the numbers alone leave open.

Why you never have to guess in Mines

In most versions of the game, a board sometimes leaves two squares that no number can tell apart: a coin toss. Mines does not deal those boards. Each board opens with a safe area already uncovered, away from the edge so it has room to spread, and before you see it a solver plays it through using only what the numbers and the mine total say. If the solver would need a guess, the board is thrown away and another one dealt.

So when you are stuck, the answer is always on the board. Go back over the edges, look at numbers in pairs, and count what is left. A fast time in Mines is never a lucky one.

The three levels

• Easy: 9×9 with 10 mines. Good for learning the patterns.
• Medium: 12×12 with 24 mines.
• Hard: 16×16 with 40 mines. Longer chains of deduction, and more counting at the end.

For now every level counts for the monthly leaderboard, which resets on the 1st of every month at 00:00 UTC.

Ready to try them? Play Mines — no account needed, and your time is measured by our server from the moment the opening area is shown.