Convert Betting Odds — American, Decimal & Fractional
Convert between American (+150), Decimal (2.50), and Fractional (3/2) odds instantly. See implied probability for any format.
Understanding the Three Odds Formats
American odds show how much you win on a $100 bet (positive) or how much you must bet to win $100 (negative). +150 means a $100 bet wins $150. -150 means you bet $150 to win $100. Decimal odds show your total return per $1 wagered, including your stake. 2.50 means $1 returns $2.50 ($1.50 profit). Fractional odds show profit relative to stake. 3/2 means you win $3 for every $2 wagered.
Implied Probability — The Key Number
Every odds format implies a probability of the outcome occurring. -110 implies 52.4% probability. +200 implies 33.3%. This is the most important number for bettors — if you believe a team has a 40% chance of winning but the implied probability is only 30% (+233), that is a value bet. The gap between your estimated probability and the implied probability is your edge.
Why Implied Probabilities Sum to More Than 100%
If you add the implied probabilities of both sides of a bet, they total more than 100%. For a typical -110 / -110 market: 52.4% + 52.4% = 104.8%. The extra 4.8% is the vigorish (vig) — the sportsbook margin. Lower vig means better odds for bettors. Pinnacle Sports typically runs 2-3% vig; DraftKings and FanDuel run 4-6%.
The best odds format for spotting value is implied probability. Train yourself to think in probabilities rather than odds — instead of seeing -150, think "60% implied." Then ask: do I believe this outcome has more or less than a 60% chance? If more, pass. If less, bet the other side.
