Odds converter: decimal, fractional, American & no-vig fair odds
Bookmakers around the world quote the same price three different ways. This free converter translates between all of them instantly — shows the implied probability, the number that actually matters — and strips the vig out of any two-way market to reveal the fair odds.
Decimal odds of 2.50 equal fractional 6/4, American +150 and a 40% implied probability. Enter any one format below and the other two appear instantly — and if you add the other side of a two-way market, the converter also returns the no-vig (fair) odds with the margin removed.
Type in any one field — the other formats update instantly. Works for any price from 1.01 up.
How the three odds formats work
Decimal odds (European)
The total return per unit staked, stake included. Odds of 2.50 turn a 100 stake into 250 back (150 profit). Used across Europe, Australia, Canada and by every crypto book we track — and by all tables on OddsDetective, because the math is cleanest.
Fractional odds (UK & Ireland)
Profit relative to stake. 6/4 means 6 units of profit for every 4 staked — bet 100, win 150 profit, collect 250. Traditional with British bookmakers and horse racing; identical information, older packaging.
American odds (US)
Two modes around the even-money point. Positive (+150): profit on a 100 stake. Negative (-200): the stake required to win 100. The favourite carries the minus sign, the underdog the plus — once you see that, the format stops being confusing.
Conversion formulas (for the curious)
decimal = 1 + american/100 (positive american)
decimal = 1 + 100/|american| (negative american)
implied probability = 100% / decimal
The implied probability line is the one to memorise: it converts any price into the win rate you must beat to profit. A bet at 2.50 only makes money long-term if the true chance is better than 40%.
| Decimal | Fractional | American | Implied probability |
|---|---|---|---|
| 1.25 | 1/4 | -400 | 80.0% |
| 1.50 | 1/2 | -200 | 66.7% |
| 1.91 | 10/11 | -110 | 52.4% |
| 2.00 | 1/1 (evens) | +100 | 50.0% |
| 2.50 | 6/4 | +150 | 40.0% |
| 3.00 | 2/1 | +200 | 33.3% |
| 5.00 | 4/1 | +400 | 20.0% |
| 11.00 | 10/1 | +1000 | 9.1% |
No-vig fair odds: what the price would be without the margin
Quoted odds always contain the bookmaker's commission. The no-vig (fair) odds are what the market would pay with that commission stripped out — the honest probability the book itself is working from. For a two-way market: divide each side's implied probability by the market's implied total, then invert. The converter does this automatically: enter your selection's price in any format, add the opposite side's decimal odds in the optional field, and you get the overround, the no-vig probability and the no-vig fair odds.
no-vig fair odds = 1 ÷ no-vig probability → 1.95 / 1.95 market → fair odds 2.00
Why it matters: the no-vig line is the cleanest benchmark for whether a price is worth taking. If a book quotes 2.10 on an outcome whose no-vig odds (computed from a sharp book's two-way market) are 2.04, you are being paid better than fair — the core signal behind closing line value in our odds comparison guide. For 1X2 and other three-way markets, the margin calculator performs the same de-vigging with a dedicated 3-way mode.
Why implied probability matters more than the format
Every odds format is a costume; implied probability is the suspect underneath. Add up the implied probabilities of every outcome in a market and you will find they exceed 100% — that excess is the bookmaker's margin, the real price of the bet. Our margin calculator does that arithmetic for any market, and our bookmaker ranking shows who keeps the excess smallest.
Implied probability is also how you compare prices across formats without mistakes. Is +145 at an American-facing book better than 6/4 at a UK one? Convert: +145 → 40.8% implied, 6/4 → 40.0%. The 6/4 quote pays more for the same outcome. Two seconds in the converter beats squinting at unfamiliar notation — especially mid-tournament, with World Cup 2026 prices moving daily.
Frequently asked questions
How do I convert decimal odds to American odds?
If the decimal is 2.00 or higher: (decimal − 1) × 100, with a plus sign — 2.50 becomes +150. If it is below 2.00: −100 ÷ (decimal − 1) — 1.50 becomes −200. The converter above does both directions automatically, including awkward in-between prices.
What do fractional odds like 6/4 mean?
Profit relative to stake: 6 units of profit for every 4 staked. A 100 bet at 6/4 returns 150 profit plus your 100 back. As a decimal that is 2.50, as American odds +150, and as implied probability 40%.
What is implied probability in betting?
The win rate a price assumes: 100% divided by the decimal odds. Odds of 2.50 imply 40%. It is the break-even threshold — if you believe the true chance is higher than the implied figure, the price is worth taking; if lower, pass.
Why do the implied probabilities of a match add up to more than 100%?
Because the bookmaker's margin is baked into the prices. A fair market sums to exactly 100%; real books sum to 102–107% on football. The excess is their commission — measure it for any market with our margin calculator, and see which books charge least in our ranking.
What are no-vig (fair) odds and how do I calculate them?
No-vig odds are the prices with the bookmaker's margin removed. For a two-way market, divide your side's implied probability by the market's implied total and invert: a 1.95/1.95 market de-vigs to 2.00/2.00. This converter computes them automatically when you enter both sides.