Tools

Human-reviewed calculators with formulas in HTML. No login. Inputs are not stored by default.

• Probability ↔ odds converter

  Convert prediction-market probabilities to decimal and American odds with clear bounds and validation — no account required.

• Expected value calculator

  Compute EV = p·net win − (1−p)·loss for a single binary stake with explicit probability and payoff inputs.

• Two-outcome arbitrage checker

  Check whether two complementary probabilities (same contract definition) imply a risk-free stake split — only for compatible definitions.

• How to compare prediction markets side by side

  A reviewed checklist for comparing up to four qualified market-event pages: definition, resolve time, provider, probability, movement, liquidity, and observation time.