Betting Odds Explained: Formats, Probability and the Margin You Really Pay
Odds are a price and a probability at the same time. This guide shows how to read every format, how to turn odds into a chance, and what we measured when we checked thousands of bookmaker prices against real results.
Decimal odds: the easiest format
Decimal odds, used across Europe, show what you get back for every unit you stake, including your stake. Odds of 2.50 on a 10 unit bet return 25 units if it wins: your 10 back plus 15 profit.
Profit = stake × (decimal odds − 1). At odds of 1.80, a 10 unit bet returns 18 units, of which 8 is profit.
Lower odds mean the bookmaker thinks the outcome is more likely. Anything below 2.00 is “odds-on”: you win less than you stake. Above 2.00 is “odds-against”.
Fractional and American odds
Fractional odds (common in the UK) show profit relative to stake: 3/2 means 3 units profit for every 2 staked. American odds use a plus or minus sign: +150 is the profit on a 100 stake, −200 is what you must stake to win 100. All three formats describe the same price:
| Decimal | Fractional | American | Implied chance |
|---|---|---|---|
| 1.25 | 1/4 | −400 | 80.0% |
| 1.50 | 1/2 | −200 | 66.7% |
| 2.00 | 1/1 (evens) | +100 | 50.0% |
| 2.50 | 3/2 | +150 | 40.0% |
| 3.00 | 2/1 | +200 | 33.3% |
| 5.00 | 4/1 | +400 | 20.0% |
| 11.00 | 10/1 | +1000 | 9.1% |
To convert yourself: decimal = fractional + 1 (3/2 becomes 1.5 + 1 = 2.50). For American: positive odds divided by 100 plus 1 (+150 becomes 2.50), negative odds as 100 divided by the number plus 1 (−200 becomes 1.50).
Odds Converter
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For education only. Odds conversions are exact; no outcome is guaranteed. 18+. Please gamble responsibly.
From odds to probability
Every price hides a probability: 1 divided by the decimal odds. Odds of 2.50 imply 40%. But add up all outcomes of one match and you get more than 100%. Take a typical match result market:
| Outcome | Odds | Implied | Fair (margin removed) |
|---|---|---|---|
| Home win | 2.10 | 47.6% | 45.4% |
| Draw | 3.40 | 29.4% | 28.1% |
| Away win | 3.60 | 27.8% | 26.5% |
| Total | 104.8% | 100% |
Those extra 4.8 percentage points are the bookmaker margin, also called the overround or vig. To find the fair probability, divide each implied chance by the total: 47.6 / 104.8 = 45.4%. That fair number is what you compare with your own estimate, as we explain in our value betting guide.
How much margin you actually pay
We measured the average margin per bookmaker and per market across all pre-match odds in our database:
| Bookmaker | 1X2 | Over/under 2.5 | Asian handicap | BTTS | Double chance |
|---|---|---|---|---|---|
| Pinnacle | 5.4% | 5.0% | 4.9% | n/a | n/a |
| Bet365 | 7.9% | 5.9% | 6.4% | 7.4% | 12.1% |
| 10Bet | 7.2% | 6.1% | 7.1% | 8.4% | 15.3% |
| Unibet | 7.8% | 7.8% | 9.0% | 8.8% | 15.6% |
Source: Daily Sport Pick odds database, Pinnacle July to October 2026 (about 14,600 stored prices), Bet365 April to October 2026 (14,600), 10Bet and Unibet April to September 2026 (8,500 each). “n/a” means the market was not in our feed for that bookmaker.
The same bet can cost three times as much depending on where and what you bet. Double chance markets carried 12 to 16% margin, against about 5% for over/under 2.5 at Pinnacle.
Margins also differ by competition. The highest we saw was the Conference League, at 9 to 10% on 1X2 at both Pinnacle and Bet365; the lowest was MLS, at 3.9% at Pinnacle. As a rule, big and liquid markets are cheaper than small ones.
Pinnacle vs Bet365: same match, different price
We compared both bookmakers on the 3,388 matches where we had a 1X2 price from each. Pinnacle offered the higher odds on 74% of outcomes, Bet365 on 22%, and 4% were equal. On average a Pinnacle price was 3.3% higher.
Did Bet365 know something Pinnacle did not? No. We scored both on how well their fair probabilities predicted the actual results (log loss, lower is better): Pinnacle 0.9940, Bet365 0.9944. Practically identical.
Both bookmakers read the matches equally well. The difference is only how much they charge for it, and over hundreds of bets 3% is the difference between a small loss and a large one.
Do odds tell the truth? Favourites vs outsiders
We grouped every Pinnacle 1X2 price from 3,484 settled matches by odds range and checked how often those outcomes actually happened:
| Odds range | Bets | Avg. odds | Fair chance | Actually won | Return |
|---|---|---|---|---|---|
| 1.00 to 1.40 | 344 | 1.25 | 75.8% | 78.8% | −1.9% |
| 1.40 to 1.70 | 649 | 1.55 | 61.3% | 62.6% | −3.3% |
| 1.70 to 2.00 | 799 | 1.85 | 51.5% | 51.8% | −4.3% |
| 2.00 to 2.50 | 1,315 | 2.24 | 42.8% | 42.4% | −5.4% |
| 2.50 to 3.20 | 1,754 | 2.87 | 33.5% | 32.2% | −7.7% |
| 3.20 to 4.00 | 2,889 | 3.58 | 26.8% | 27.9% | −0.4% |
| 4.00 to 6.00 | 1,953 | 4.67 | 20.6% | 19.9% | −8.1% |
| 6.00 to 10.00 | 547 | 7.35 | 13.2% | 13.2% | −5.8% |
| 10.00 or more | 202 | 15.13 | 7.0% | 2.5% | −68.2% |
Source: Pinnacle pre-match odds, July to October 2026, latest stored price before kick-off, 1 unit per bet. Bet365 showed the same pattern, with most groups a few points worse.
Up to odds of about 10, the fair probabilities were remarkably close to reality. Then it breaks: outcomes priced at 10.00 or more won only 2.5% of the time, not the 7% the odds suggested. That is a small group of 202 bets, but both bookmakers show the same gap. Backing all of them lost −68% at Pinnacle and −71% at Bet365. This is the well-known favourite-longshot bias: bettors love big prices, so bookmakers can offer them short.
The group at 3.20 to 4.00 did best, close to break-even, and it is largely made up of draws. Backing the draw in every match returned −1.4% at Pinnacle, against −7.5% for always backing the home team and −8.5% for the away team:
| Strategy | Pinnacle won | Pinnacle return | Bet365 won | Bet365 return |
|---|---|---|---|---|
| Always the home team | 44.0% | −7.5% | 44.4% | −8.3% |
| Always the draw | 25.9% | −1.4% | 25.7% | −5.3% |
| Always the away team | 30.1% | −8.5% | 29.9% | −11.4% |
That does not make the draw a strategy: it is one part-season, and −1.4% is still a loss. It does show where the market is least generous: big outsiders.
Asian handicap odds in short
Asian handicap gives one team a head start to remove the draw. Whole lines (−1) can end level and refund your stake, half lines (−0.5, −1.5) always produce a winner, and quarter lines (−0.25, −0.75) split your stake over the two nearest lines, so you can win or lose half. With two outcomes instead of three, the margin was lower than on 1X2 at Pinnacle, Bet365 and 10Bet. The full explanation, with worked examples, is in our Asian handicap guide.
How to use odds sensibly
- Always convert to probability. 1 divided by the odds, then remove the margin. If you cannot say what chance a price implies, you cannot judge it.
- Compare bookmakers. In our data the gap between Pinnacle and Bet365 averaged 3.3%, more than most bettors could ever hope to beat the market by.
- Prefer cheap markets. At Pinnacle and Bet365, over/under and Asian handicap carried 5 to 6.5% margin; double chance cost 12 to 16% wherever it was offered.
- Be wary of big prices. Odds of 10.00 or more looked generous and were the most expensive bets in our data.
- Bet only what you can afford to lose. See our bankroll guide, and if betting stops being fun, BeGambleAware offers free, confidential help.
Frequently asked questions
What do decimal odds of 2.00 mean?
For every 1 unit you stake you get 2.00 back if the bet wins: your stake plus 1.00 profit. Odds of 2.00 imply a 50% chance before the bookmaker margin is taken into account.
How do you calculate implied probability from odds?
Divide 1 by the decimal odds. Odds of 2.50 imply 1 / 2.50 = 40%. Because the bookmaker adds a margin, the implied probabilities of all outcomes add up to more than 100%; scale them back to 100% to get the fair probabilities.
What is the bookmaker margin?
The part of every market the bookmaker keeps. Add up 1 divided by each price: anything above 100% is margin. In our data Pinnacle charged about 5% on 1X2, Bet365 about 8%, and double chance markets cost 12 to 16%.
Which bookmaker has the best football odds?
In our comparison of 3,388 matches, Pinnacle offered higher odds than Bet365 on 74% of outcomes, on average 3.3% higher, while both predicted results equally well. Prices change constantly, so compare before every bet.
Are long odds good value?
Rarely. In our data, outcomes priced at 10.00 or more won 2.5% of the time while the fair odds suggested 7.0%. Backing all of them would have lost about two thirds of the stakes at both Pinnacle and Bet365.
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