Odds Converter & Vig Calculator
Type odds in any format and see the rest — plus the probability the price implies, and how much margin the bookmaker built in.
Convert odds
If it wins
—profit
Bookmaker margin (vig) & fair odds
Enter the odds for every outcome of one market (decimal or American, 2–3 outcomes).
Quick reference
| Decimal | Fractional | American | Implied |
|---|
The conversions
Implied probability = 1 ÷ decimal odds
Decimal = fractional + 1 (3/2 → 2.50)
American +X → decimal = 1 + X/100 American −X → decimal = 1 + 100/X
Overround = Σ implied probabilities − 100%
A standard −110 / −110 line implies 52.38% for each side — 104.76% in total. That extra 4.76% is the overround; it is why a bettor needs to win 52.38% of such bets just to break even. Full explanation in Odds Formats Explained and Sports Betting Math.
Reality check: implied probability is the price, not the truth. A bet only has positive expected value if your honest estimate of the probability exceeds the implied figure — and the margin makes that rare.