Payoff Matrix Calculator

Change the incentives. See who wants to move. Explore pure and mixed Nash equilibria in a two-player, two-strategy game — free, without signing in.

Each player prefers to defect, even though both would earn more by cooperating.

Game title

Payoff unit

Row player

Column player

Two players choose simultaneously. Each cell gives the row player’s payoff first, then the column player’s. Higher is better for each player. Use whole numbers from −1,000,000 to 1,000,000.

Edit both strategies and all eight payoffs.
	Column player’s first strategy	Column player’s second strategy
Row player’s first strategy	Row payoff, row 1, column 1 Column payoff, row 1, column 1	Row payoff, row 1, column 2 Column payoff, row 1, column 2
Row player’s second strategy	Row payoff, row 2, column 1 Column payoff, row 2, column 1	Row payoff, row 2, column 2 Column payoff, row 2, column 2

Submit edits to update the analysis and lesson. The address bar then holds a shareable link to this exact game; do not put private information in its labels.

Analyzed game

Prisoner’s dilemma

A boxed cell is a pure Nash equilibrium. Underlining marks a best response, including ties. Payoffs are in points.

Row player chooses a row; Column player chooses a column. Each pair reads (Row player, Column player).
	Cooperate	Defect
Cooperate	3,3	0,5 Best response for Column player.
Defect	5,0 Best response for Row player.	1,1 Best response for Row player. Best response for Column player. Nash equilibrium

1 pure Nash equilibrium

In each boxed cell, neither player gains by switching alone. An underline may tie another payoff: a best response need not be unique.

All equilibrium probabilities

p = probability Row player chooses Cooperate. q = probability Column player chooses Cooperate. The other strategy gets 1 − p or 1 − q.

p = 0; q = 0

An interval includes both endpoints. Every combination within a listed pair of intervals is an equilibrium; the full list includes pure and mixed strategies.

Why randomize? Try a mixture.

Move one player’s probability and watch the other player’s incentives change. These are trial choices, not necessarily an equilibrium. They do not alter your game or lesson. Interactive controls require JavaScript.

Row player: choose Cooperate 50% of the time

Column player’s expected payoff for each pure strategy

Cooperate: 1.50 points
Defect: 3.00 points

Column player: choose Cooperate 50% of the time

Row player’s expected payoff for each pure strategy

Cooperate: 1.50 points
Defect: 3.00 points

What this calculator does — and does not tell you

A Nash equilibrium is a pair of strategies where neither player can improve their expected payoff by changing alone. It need not be fair, best for the pair, or a prediction of what students will actually choose.

This solver covers two players with two strategies each, including ties, weak best responses and infinitely many equilibria. It assumes each player maximizes their stated numerical payoff. It does not solve larger games, sequential games or repeated-game incentives.

The mixed-strategy calculation makes each player indifferent between the strategies they randomize over. Equilibrium probabilities are exact reduced fractions; the optional trial-mixture display is rounded.

For a worked mathematical introduction, see MIT’s mixed-strategy lecture. Ready to teach? Explore game theory classroom activities, then use the exact analyzed game below.

Teach this exact game

Put it on a slide and your audience joins from their phones — no app and no accounts for them. Free to start.

Teach this exact game

Run it live, not just on paper

Use this result in a live activity your audience joins from their phones — no app, no accounts for them.

Create a presentation