How to Play Dots and Boxes: Strategy & Chain Tips

Dots and Boxes appeared in the 19th century. Édouard Lucas (the same mathematician who invented Tower of Hanoi) described it in 1889 under the name la pipopipette. Despite the kid-friendly appearance, top-level play involves sophisticated chain counting. Here’s how to play strategically.

The short version of how to play Dots and Boxes: take turns drawing one line between neighboring dots, claim a box when you draw its fourth side, and move again whenever you claim one. Most boxes at the end wins. Everything else is about who is forced to open the long chains.

Key takeaways

Completing a box earns you another move, which is why the endgame can swing in a single turn.
Never draw the third side of a box while a safe move remains.
The double-cross (giving back two boxes) keeps control of the endgame.
Counting long chains early tells you whether you are winning the fight for control.

The rules

Grid of dots (4×4 dots, which makes 3×3 boxes, or larger). Players take turns connecting two adjacent dots with a line. When a player completes the fourth side of a box, they claim that box AND get to draw another line. Last few moves can chain rapidly.

Game ends when all boxes are claimed. Player with most boxes wins.

Lines are only horizontal or vertical, between dots that sit next to each other; no diagonals. On paper, players usually write their initial inside each box they claim. On a board with an odd number of boxes, such as 3×3 or 5×5, a tie is impossible.

How big is each board?

Dots	Boxes	Total lines	Feel
4×4	9 (3×3)	24	Quick; good for learning
5×5	16 (4×4)	40	The standard casual size
6×6	25 (5×5)	60	Room for several chains
7×7	36 (6×6)	84	Long, chain-heavy endgames

Strategy 1: Don’t draw the 3rd side of a box

If a box has 2 sides drawn, drawing the 3rd side gives opponent a free turn to claim that box. Avoid this whenever possible.

Beginner mistake: just drawing random lines without checking the side count of adjacent boxes.

Early in the game almost every line is safe. The middle game is a race to make the last safe move: as safe lines run out, whoever is forced to draw a third side starts giving boxes away.

Strategy 2: The double-cross

Late in the game every move hands boxes to someone. A chain is a row of boxes that each already have two sides drawn, so one line opens the whole thing. When your opponent opens a long chain for you, you don’t have to take it all.

The double-dealing move: claim every box in the chain except the last two, then draw the line at the far end so those two boxes are left as a pair your opponent can take with a single line (that line is the double-cross). They take the two boxes, but then they must move again and open the next chain for you. Giving up two boxes keeps you in control.

A worked example

Suppose the board has come down to two chains: one of five boxes and one of six. Your opponent must open one, say the five. If you greedily take all five, you have to move next and open the six-chain, so they take six: you finish 5–6 on those chains. If you take three and double-deal the last two, they get two boxes but must open the six-chain for you: you finish 9–2.

Loops work the same way, but cost four

A loop is a chain that closes on itself, so opening it lets the other player take every box. To keep control in a loop, take all but the last four boxes and leave them as two pairs. That costs more than a chain, which is why loops can shift the endgame count.

Strategy 3: Chain counting

Count the ‘long chains’ (chains of 3 or more boxes). The parity of long chains decides who gets control of the endgame, which usually decides the game.

Elwyn Berlekamp’s long chain rule, stated simply: on boards with an odd number of boxes per side (3×3 or 5×5 boxes), the first player wants an EVEN number of long chains and the second player wants an ODD number.

On boards with an even number of boxes per side (4×4 or 6×6 boxes), reverse it: the first player wants ODD, the second wants EVEN. Loops and short chains complicate the count, so treat this as a guide rather than a guarantee.

An easy way to remember it: the first player wants the number of dots plus the number of long chains to be even. That covers every rectangular board, not just squares.

Board (dots)	Total dots	First player wants	Second player wants
4×4	16	Even long chains	Odd long chains
5×5	25	Odd long chains	Even long chains
6×6	36	Even long chains	Odd long chains
7×7	49	Odd long chains	Even long chains

Top players manipulate move order to force the long-chain parity in their favor. This is a deep skill. Berlekamp wrote a whole book on it, The Dots and Boxes Game: Sophisticated Child’s Play, and the game also gets detailed treatment in Winning Ways for your Mathematical Plays, which he co-wrote with John Conway and Richard Guy.

Strategy 4: Sacrifice for parity

If chain count is going against you, deliberately sacrifice a box or two early to change how the chains form. You give up a little now to win control of the long chains later, which can be worth far more.

This counter-intuitive move is why Dots and Boxes is considered a deep game. Pure greed (take every box available) loses to chain-counting.

Sacrifices work best in the middle game, while the chains are still forming. A single line can split one long chain into two short ones, or join two short ones into a long one, and either change flips the parity.

Strategy 5: Endgame

Once all ‘safe’ moves are exhausted, each line drawn gives opponent at least 1 box. Count the chain lengths you could open; give away the shortest one first.

Skilled players count the whole endgame in advance. Beginners usually look only one move ahead.

When you have to hand over a two-box chain, draw the line between the two boxes rather than at one end. That leaves two separate single boxes and takes away your opponent’s chance to double-deal, so they simply take both and must then move again. Berlekamp calls this the hard-hearted handout.

Common mistakes to avoid

Taking every box on offer. Greed is right most of the time, but not when it means opening a long chain next.
Counting boxes, not chains. In the endgame, the number and length of chains matters more than the current score.
Forgetting the extra move. After you claim a box you must draw another line, and that line can be the one that opens the next chain.
Opening the long chain first. Give away short chains and single boxes before long ones.

Practice

Play our Dots and Boxes on grids from 4×4 to 7×7 dots, against the CPU or a friend. The Hard CPU takes any box it can, avoids drawing third sides while safe moves remain, and then tries to hand over as few boxes as possible, so it is a good sparring partner for practicing the double-dealing move.

How the three CPU levels behave:

Easy takes a box when one is available and otherwise draws a random line, third sides included.
Medium also avoids drawing third sides while it can, but picks at random once safe moves run out.
Hard adds endgame care: when every move gives something away, it opens the line that hands you the fewest boxes in a row.

No level ever declines a box, so the CPU never double-deals. Once you take control of the endgame, it will grab every chain you hand it and then have to open the next one. You always move first against the CPU, and the game opens on 5×5 dots, which has 25 dots: by the rule above, you want an odd number of long chains. Click or tap between two dots to draw a line.

Frequently asked questions

Do you get another turn after completing a box?

Yes. Completing a box claims it and gives you another line straight away. If that line completes another box, you go again, which is how one turn can sweep a whole chain.

What is the best first move in Dots and Boxes?

Early on, nearly every line is safe, so the exact first move matters little. What matters is avoiding third sides and steering the number of long chains toward the parity that favors you.

What is a double-cross in Dots and Boxes?

It is a single line that completes two boxes at once. It happens when a player declines the last two boxes of a chain, leaving them as a pair; the opponent takes both with one line but then has to move again.

Is Dots and Boxes a solved game?

Small boards have been analyzed in depth by computer, but larger boards are still played on judgment. For human play, the long chain rule and the double-cross take you most of the way.

Can two people play Dots and Boxes online?

Yes. Our version has a 2 Players mode for passing one device back and forth, alongside the vs CPU mode with Easy, Medium and Hard levels.

Keep playing

Learn to avoid third sides first, then the double-cross, then chain counting; that order matches how most players improve. If you like games decided by parity and forced moves, try Nim or Hex, browse more logic games, or take a break with the dino game.

How to Play Dots and Boxes — Long Chain Theory + Double-Cross