Free prediction market calculators

Work out the odds, the expected value and the right size for a trade before you place it, and check how much room your prop firm account has left. Free, no sign-up.

Odds calculator
Turn a contract price into implied probability and decimal, American or fractional odds.
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Expected value calculator
See whether a trade is worth taking after fees, and the probability you need to break even.
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Kelly criterion calculator
Work out how much of your bankroll to put on one contract, with fees and a position cap.
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Fee calculator
Work out the trading fee on an order and see why cheap contracts pay the most in fees.
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Drawdown calculator
Find the balance you must stay above under static or trailing drawdown, and your room left.
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New to prediction market prop trading? Start with the guides.