Flip two coins simultaneously and see both results instantly. Tracks all four possible outcomes — HH, HT, TH, TT — across your session so you can verify each has a 25% chance.
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Coin 1
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Coin 2
Click to flip both coins
Press Space or Enter
Session outcomes
HH0
HT0
TH0
TT0
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When you flip two coins at once, there are four equally likely outcomes: Heads-Heads (HH), Heads-Tails (HT), Tails-Heads (TH), and Tails-Tails (TT). Each outcome has exactly a 25% probability — the two coins are independent events, so the result of coin 1 has no effect on coin 2. This makes two-coin flips a classic entry point for combined probability: you multiply independent probabilities (0.5 × 0.5 = 0.25) and list sample spaces systematically.
At least one head: the 75% rule
A common probability question is: "What is the probability of getting at least one head in two flips?" The answer is 75% — three of the four outcomes (HH, HT, TH) contain at least one head. Only TT has none. This illustrates the complement rule: P(at least one head) = 1 − P(no heads) = 1 − 0.25 = 0.75. Run the session tally for 20 or more flips and watch the TT count settle around one-quarter of your total.
Classroom and game uses
Two-coin flips appear in probability curricula from middle school through AP Statistics for teaching sample spaces, independent events, and the multiplication rule. For games, two simultaneous coins create four-way decisions (each outcome maps to a choice), or a "double-or-nothing" flip where both heads is the jackpot. The session tally demonstrates empirical vs. theoretical probability in real time — no spreadsheet required.
Frequently asked questions
What are the possible outcomes of flipping 2 coins?
There are four possible outcomes when flipping 2 coins: Heads-Heads (HH), Heads-Tails (HT), Tails-Heads (TH), and Tails-Tails (TT). Each outcome has exactly a 25% probability because the two coins are independent events — the result of one coin has no effect on the other.
What is the probability of getting two heads?
The probability of getting two heads (HH) when flipping 2 coins is 25%, or 1 in 4. Since each coin independently has a 50% chance of heads, you multiply the probabilities: 0.5 × 0.5 = 0.25. Run the session tally for many flips and the HH count should approach one-quarter of your total.
What is the probability of at least one head in 2 flips?
The probability of getting at least one head when flipping 2 coins is 75%. Three of the four possible outcomes contain at least one head: HH, HT, and TH. Only TT has no heads. This illustrates the complement rule: P(at least one head) = 1 − P(no heads) = 1 − 0.25 = 0.75.
How is flipping 2 coins used in probability class?
Two-coin flips are a classic classroom introduction to combined probability. They teach sample spaces (listing all possible outcomes systematically), independent events (one coin's result doesn't affect the other), and the multiplication rule (multiply individual probabilities to get the combined probability). Students can verify theoretical probabilities empirically by running many flips and watching the tally converge toward the expected 25% per outcome.
Who uses this tool
Students
Learn combined probability hands-on — flip repeatedly and watch each of the four outcomes converge toward its expected 25% frequency.
Teachers
Demonstrate sample spaces and independent events live. The session tally builds empirical probability data without any setup.
Game players
Make four-way decisions instantly — assign each outcome to a choice and let the coins decide with perfect fairness.
Decision makers
Use HH/TT for binary decisions with a double-confirmation mechanic — both coins must agree for an outcome to count.