Prediction market odds converter
Translate a price for a binary contract paying $1 into other odds formats. Use the price you can actually buy at when comparing contracts; a displayed midpoint is not necessarily an available fill.
Odds converter
A prediction-market price in cents is already an implied probability. This is the table you need when a sportsbook quotes the same event in American odds and you want to know which side is cheaper.
At 42¢ you pay $0.42 for a contract that settles at $1. The fee-free break-even probability is 42.0%; costs raise that threshold.
How to use this calculator
- Enter the purchase price between 1¢ and 99¢.
- Read the equivalent probability and odds formats.
- Before comparing two venues, check that the outcomes and settlement rules match.
Formula
- p = price in cents / 100
- Decimal odds = 1 / p
- American odds = 100 × (1 − p) / p when p < 0.5; otherwise −100 × p / (1 − p)
- Fractional odds = (1 / p − 1) to 1
Worked example
At 40¢, implied probability is 40%, decimal odds are 2.50 and American odds are +150. A $40 purchase represents 100 contracts: a winning settlement pays $100, including the $40 cost. The gross profit is $60, before fees.
Assumptions and limitations
The conversion assumes a $1 winning payout and zero losing payout. Implied probability is a translation of price, not an independent forecast. Fees, slippage and different settlement rules change the comparison.
Common questions
Does a 40¢ price mean a guaranteed 40% chance?
No. It is the probability implied by that price under a simple binary payout model. The actual probability can differ.
Which price should I enter?
Use the expected execution price. For an immediate purchase that is usually an available ask, subject to sufficient size, rather than a headline midpoint or last trade.
Examples are our arithmetic illustrations. Linked references explain the underlying market mechanics or model; they do not endorse a result or a trade.