What do Minesweeper numbers mean? Neighbours, diagonals and safe cells

A Minesweeper number tells you exactly how many mines touch that cell. It counts all neighbouring cells, including diagonals. It does not count the whole row, and it does not point towards a particular mine.

The eight neighbours of a cell

Imagine a three-by-three square with an opened cell in the centre. Every other cell in that square touches the centre. There are three above it, two beside it and three below it: eight possible neighbours in total.

M???2???M

In this example, the central 2 touches two known mines. Its count is complete, so its six other neighbours are safe. The mines are marked here to explain the rule; in an actual puzzle, you must prove a hidden cell is a mine before relying on it.

The edge of a board changes how many neighbours exist. A corner has at most three neighbours. A non-corner edge cell has at most five. The number still counts all touching mines, but there are fewer possible places for them.

What do 1, 2 and 3 through 8 mean?

• 1: exactly one neighbour contains a mine.
• 2: exactly two neighbours contain mines.
• 3 through 8: the same rule, with that many touching mines.
• No number: zero touching mines. Many versions show this as an empty cell rather than a printed 0.

The number is exact, not a maximum. A 2 cannot touch one mine or three mines. This is why clues can rule out cells even when those cells have not been opened.

Count the mines that are still missing

For a useful deduction, subtract the mines you have already proved from the number on the cell. Then compare the remaining count with the hidden neighbours that are not yet accounted for.

Suppose an opened 2 touches one proved mine and three other hidden cells. One of those three must contain the remaining mine, but that clue alone does not say which one. You need another clue.

If the same 2 touches two proved mines, every other unaccounted-for neighbour is safe. If it touches one proved mine and just one other hidden cell, that hidden cell must be the second mine.

When one number is not enough

Two neighbouring numbers often share some hidden cells. Consider a 1 that touches only A and B, and a nearby 2 that touches only A, B and C. The 1 tells you that A and B contain one mine between them. The 2 needs two mines altogether, so C must contain the other mine.

That deduction does not tell you whether A or B is the first mine. It tells you something narrower and still useful: C is certain. Keep the unresolved pair unresolved until another clue separates it.

This is the idea behind many Minesweeper patterns. The exact cells touching each clue matter more than the digits you happen to see in a row.

Three common reading mistakes

• Forgetting diagonals. A mine diagonally touching a 1 satisfies that 1.
• Counting a mine twice for one clue. A single mine contributes one to that clue’s count, even if it looks close to several sides.
• Treating a flag as a fact. A wrong flag can lead to another wrong move. Return to the clue that justified it.

A mine may legitimately count towards several different numbers. Each clue has its own neighbourhood; satisfying one clue does not remove the mine from another clue’s count.

Practice the rule before chasing speed

Pick a number and trace its full neighbourhood. Ask how many mines it still needs and how many unknown cells remain. Keep moving only when you can explain the result. If you are completely new, start with how to play Minesweeper and the small practice puzzle.