Fermi Poker Rules
What is Fermi Poker?
Fermi Poker is like poker, but instead of cards, players make guesses about questions that seem unknowable at first — like "How many humans have ever lived?"
Players write down secret guesses, bet on their answers, get helpful hints, bet again, and the closest guess wins.
What Do You Need?
At least one other person physically present to play with you, but it's more fun with larger groups
Something to write down guesses, and poker chips or other play money
How to Play
Question reveal
Before seeing the question, each player must put one or more chips into the pot (the size of this mandatory bet should increase every other question). Then the question is revealed, for example: "How many chickens are killed every year for meat?"
Secret guesses
Each player secretly writes down their guess as a range (e.g. 20 billion to 100 billion). Alternatively, you can also require everyone to play with exact numbers instead of ranges.
Betting round #1
Betting moves clockwise, starting with a different player each question. On your turn, you may check (pass without betting, if no one has bet yet), raise (bet more than the current highest bet), call (match it), or fold (drop out and forfeit the pot). Betting continues until all players have either folded or matched the highest bet.
Hint #1 (+ Betting round #2)
When the first betting round is over, the first hint is revealed. The hint helps all players to estimate how good the initial guess is. Then the second betting round is played, as in the first betting round, players can now perform the same actions.
Hint #2 (+ Betting round #3)
After the second betting round is over, a second hint is revealed and the third betting round is played.
Answer reveal
Before the fourth and final betting round, the answer to the guessing question is revealed so that all players know if they are close to the answer.
Betting round #4
After the answer reveal, there is a fourth and final betting round.
Showdown
When the final betting round ends with two or more players still in, everyone left reveals their guess. Folded players—and anyone who won before it came to the showdown—don't have to reveal their guess. The pot goes to the player with the narrowest range that contains the correct answer; if several ranges are equally narrow, those players split the pot. If no player has the correct answer inside their range, whoever's median of their range is closest to the answer wins.