Odds converter: American, decimal, fractional & implied probability
Type a value in any field — the others update instantly. Below it, the vig calculator takes both sides of a market and shows the bookmaker's margin and the fair, juice-free line.
Enter odds in any format above.
Two-way vig calculator
Enter both sides to see the vig and the no-vig fair line.
How the conversions work
Decimal odds are total return per $1 staked. American odds describe profit relative to $100: negative numbers are the stake needed to win $100, positive numbers the profit on a $100 stake. Implied probability is 1 ÷ decimal. Because sportsbooks price both sides so implied probabilities sum past 100%, the posted number always overstates the true chance — that overage is the vig. Prediction markets show the same quantity as a price in cents; we compare the two models in sportsbook vs prediction market and break down venue fees in Kalshi vs Polymarket fees.
FAQ
- What does +200 mean?
- $100 stake → $200 profit. Decimal 3.00, implied 33.3%.
- What does -110 mean?
- Stake $110 to win $100. Decimal 1.91, implied 52.4% — the 2.4% over half is vig.
- How much vig is normal?
- Standard two-way spreads run about 4.5% total (both sides -110). Anything above ~6% is expensive.
- Why do both sides add past 100%?
- That's the bookmaker margin. Divide each side by the total to recover fair probabilities.
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