Edge = 1 − (cheapest YES cost + cheapest NO cost). Costs are per $1 of payout, net of the fees above. Betfair commission is off by default so the number matches the dashboard.
Amounts are commission-correct so both outcomes balance. Set GBP/USD to the rate your dashboard uses. Whole contracts on Kalshi/Polymarket, pennies on Betfair — the realized "if YES / if NO" reflects that rounding.
Type into any field — the rest update live. Implied probability is the vig-free 1/decimal (a single selection, no overround). Price is that same probability as a 0–1 contract price, so 62¢ ↔ 1.61 decimal ↔ 61.9%.