Prisoner's Dilemma Calculator

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Choose a preset to load standard payoff values, or pick Custom to enter your own.
Payoff when you defect and your opponent cooperates. Must be the highest value (T > R > P > S).
Payoff when both players cooperate.
Payoff when both players defect (the Nash equilibrium outcome).
Payoff when you cooperate but your opponent defects. Must be the lowest value.
Player A's decision rule for each round.
Player B's decision rule for each round.
How many times the two players interact. Use 1 for a one-shot game.
rounds
Player A total scoreHighly cooperative
30

Cumulative payoff for Player A across all rounds

Player B total score30
Cooperation rate1%
Player A avg per round3
Player B avg per round3
Nash equilibrium outcome?No - at least one player cooperated in the last round
Pareto optimal outcome?Yes - mutual cooperation was the most common outcome
Single-game outcomeMutual cooperation: A gets 3, B gets 3
Player A33
Player B33

Difference: 0 (Player B higher)

  • Total score
  • Avg per round

Both players scored equally.

  • Over 10 rounds, Player A scored 30.0 and Player B scored 30.0.
  • Mutual cooperation occurred in 100% of rounds.
  • High mutual cooperation suggests the strategies are sustaining a cooperative equilibrium, which maximizes joint welfare over time.

Next stepTry pairing Tit for Tat vs. Always Defect, then vs. Tit for Tat, to see why reciprocal strategies perform well in tournaments.

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