How do I convert between odds formats?

To convert American to decimal: positive odds → (odds/100) + 1; negative odds → (100/|odds|) + 1. To convert decimal to American: if decimal ≥ 2.0 → (decimal - 1) × 100 with a plus sign; if decimal < 2.0 → -100 / (decimal - 1). Most sportsbooks let you switch formats in your account settings, so manual conversion is rarely needed.