How to Play Intermediate Minesweeper

Intermediate Minesweeper is played on a 16×16 grid of 256 squares with 40 mines hidden at random — the classic mid-level board. The rules are identical to Beginner: reveal squares, read each number as the count of touching mines, and clear all 216 safe squares without opening a mine. The larger board and higher mine density make combined-number logic and chording essential. This page explains the layout, the key patterns and how to play for speed.

Step by step

Clear an opening. Your safe first click on the 16×16 grid opens an area. Work outward from it, reading the numbers on its border.
Combine overlapping numbers. Two numbers that share squares often prove a mine or a safe square that neither could alone. Look for 1-1 and 1-2-1 patterns first.
Flag and chord. Flag the mines you have proven, then click a satisfied number to open all its other neighbours at once. Chording is how you clear the 16×16 board quickly.
Open all 216 safe squares. Reveal every square that is not one of the 40 mines to win. Your time is saved so you can beat it next round.

Strategy

Numbers rarely solve alone at this size — read them in pairs. The 1-2-1 pattern along an edge, and two touching numbers whose difference pins down a shared square, are the bread and butter of Intermediate. Flag mines you are sure of, then chord the numbers around them to sweep whole regions fast. Keep moving through the easy areas first and come back to the tangles; opening more of the board usually adds the number you were missing. Speed comes from chording confidently, not from clicking faster.

Frequently asked questions

What are the exact Intermediate dimensions?

A 16-by-16 grid, 256 squares in total, seeded with 40 mines. That leaves 216 safe squares to clear. It is the standard Intermediate configuration used since the original Windows Minesweeper.

Which patterns should I learn first?

The 1-1 pattern (a 1 next to another 1 along a wall tells you a specific square is safe) and the 1-2-1 pattern (which pins the two mines under the 1s and clears the middle). At Intermediate size these appear constantly and turn slow guessing into instant deductions.

How does chording work on this board?

When the number of flags around a revealed number equals that number, click the number to auto-open all its remaining neighbours. On the denser Intermediate board this clears space far faster than single clicks, but a misplaced flag will open a mine, so only chord once your flags are proven.

Is 40 mines a lot for a 16×16 grid?

It works out to roughly one mine per six or seven squares — noticeably tighter than Beginner. That density is what makes Intermediate the true “standard” game: hard enough to need technique, forgiving enough to finish in a few minutes.

How do I avoid the end-game 50/50?

On random boards you sometimes cannot — two squares are equally likely and only one is a mine. The no-guess mode removes that entirely by only serving boards our solver has proven can be completed with logic alone, so your losses come from missed deductions, not luck.

Play Intermediate Minesweeper →