How to win at Dots and Boxes

By Playashe. The numbers on this page come from games between the bots of Inkline, run on 4 November 2026.

Most games of Dots and Boxes are not won by taking boxes early. They are won at the end, by making the other player open the first long chain. Four ideas get you there.

1. Never draw the third side of a box

A box with three sides drawn is a gift: the next player closes it and draws again. At the start, draw lines that leave every box with two sides or fewer. These are safe lines. Whoever runs out of safe lines first has to give boxes away.

Three sides drawn. Whoever moves next takes this box with the dotted line.

2. Count the chains

When the safe lines are gone, the boxes left form chains: rows of boxes where taking one box gives you the next. A chain of three boxes or more is a long chain. A chain that closes on itself is a loop.

A long chain of four boxes. A line drawn inside it lets the other player take all four.

3. Take all but two

When your opponent opens a long chain for you, take every box but the last two. Then, instead of taking them, draw the line at the far end of the chain. Now one line closes both last boxes at once. Your opponent takes those two, but must then draw another line, and when only long chains are left, that line opens the next chain for you. This is called the double dealing move.

Your opponent opened the chain on the left. You took two boxes, then drew the line at the far right instead of taking the last two. The dotted line now takes both, and whoever draws it must move again.

In a loop, the same move keeps back four boxes instead of two. Giving away two boxes, or four in a loop, to win the next chain is the whole trick. The player who can keep doing it is in control.

4. The long chain rule

Since the player who must open the first long chain usually loses, the fight in the middle of the game is over how many long chains there will be:

If the board has an even number of rows of boxes and an even number of columns, the first player wants an odd number of long chains, and the second player an even number.
Otherwise, the first player wants an even number of long chains, and the second player an odd number.

Loops do not count as long chains. On the boards of Inkline, that gives:

3 by 3 and 5 by 5: the first player wants an even number of long chains.
4 by 4 and 6 by 6: the first player wants an odd number of long chains.

What the bots of Inkline show

Inkline has three bots. Easy plays close to random. Medium takes every box it is offered and avoids giving boxes away, so it never gives two boxes back. Hard plays like Medium until the board is small enough, then searches every ending, and gives two boxes back when that wins more.

We let them play each other on 4 November 2026: 1,000 games for each pairing, each bot moving first in half of them.

On 5 by 5, Hard beat Medium in 992 games out of 1,000.
On 4 by 4, Hard beat Medium in 949 games, lost 9 and drew 42.
On 3 by 3, Hard beat Medium in 977 games out of 1,000 and lost 23.
On 5 by 5, Medium beat Easy in 997 games out of 1,000.
On 5 by 5, between two Hard bots, the player who moved first won 522 games out of 1,000, close to even.

The habit of Medium, taking every box it is offered, is the habit this guide asks you to drop.

Practice in Inkline

Play Medium on 3 by 3 until you never draw a third side by accident.
Play Hard on 3 by 3 and 4 by 4. After a game you lose or draw there, Inkline can show you the turning point: the move where your result slipped, with a dotted line that was better.
Play today's board, a 5 by 5 board against Hard, and count the long chains before the safe lines run out.

Playing on paper? Print the Dots and Boxes sheet.

Sources

Elwyn Berlekamp, The Dots and Boxes Game, A K Peters, 2000.
Some Strategy for Dots and Boxes, on the mathematics site of the University of California, Los Angeles: the long chain rule as given here.
Dots and boxes, Wikipedia: the history of the game.