Odds & probability converter

Reading the formats

• Contract cents & implied probability are effectively the same number on a prediction market: a 64¢ Yes share carries a 64% implied chance.
• Decimal odds show your total return per $1 staked, including the stake — 1.56 means $1 becomes $1.56 on a win.
• Fractional odds show profit to stake — 9/16 means you win $9 for every $16 risked.
• American odds use a $100 reference: a minus figure is how much you stake to win $100; a plus figure is how much $100 wins.

Once you have the price, the profit calculator turns any stake into shares, payout and ROI. For the bigger picture, see how prediction markets work.

A worked example

Say a market has Yes trading at 64¢. That is a 64% implied probability, decimal odds of about 1.56, fractional odds of roughly 9/16, and American odds of around −178. Stake $100 and a win returns about $156 — your $100 back plus $56 profit — while a loss costs the $100. The break-even win rate is exactly the price: at 64¢, you need to be right more than 64% of the time for this to pay off over many trades. That last point is the one most newcomers miss, and it is why converting odds to a probability is the first habit worth building.

Prices and probabilities move constantly as news arrives and other traders take positions, so treat any figure as a snapshot. If a market looks mispriced relative to your own honest estimate, that gap — not the raw odds — is where an edge comes from.