Observed market data
How Much Margin Was in Premier League Opening-Weekend 1X2 Markets?
We measured the 1X2 book percentage on all 10 matches from the opening round of the 2025/26 Premier League season. The aim was simple: replace a generic explanation of overround with a real market snapshot that readers can reproduce.
What we measured
For each opening-weekend match we took three sets of decimal prices from the Football-Data.co.uk Premier League CSV:
- Bet365 opening prices for home, draw and away.
- Average opening prices across the bookmakers included in the source file.
- Maximum opening prices for each outcome, representing the best listed price available across the source's bookmaker set.
We then converted each price to implied probability and added the three probabilities together.
Implied probability = 1 ÷ decimal odds × 100
Book percentage = home implied probability + draw implied probability + away implied probability
Overround = book percentage − 100%
A 105.50% book therefore contains 5.50 percentage points above a theoretical 100% book. That figure is not the bookmaker's guaranteed profit margin; it is a measure of the pricing built into the market.
The 10-match results
| Match | Bet365 book | Market-average book | Best-available book |
|---|---|---|---|
| Liverpool v Bournemouth | 105.35% | 105.15% | 100.54% |
| Aston Villa v Newcastle | 107.50% | 105.58% | 100.94% |
| Brighton v Fulham | 105.13% | 105.28% | 102.95% |
| Sunderland v West Ham | 104.63% | 105.38% | 102.82% |
| Tottenham v Burnley | 105.28% | 105.87% | 101.95% |
| Wolves v Man City | 106.02% | 105.44% | 100.90% |
| Chelsea v Crystal Palace | 107.05% | 105.55% | 102.15% |
| Nott'm Forest v Brentford | 104.33% | 105.43% | 102.19% |
| Man United v Arsenal | 106.84% | 105.85% | 101.61% |
| Leeds v Everton | 105.65% | 106.02% | 101.36% |
The pattern is clearer than any one match. Bet365's opening book ranged from 104.33% to 107.50%. The market-average book was much tighter as a range, from 105.15% to 106.02%. The best available prices across bookmakers ranged from 100.54% to 102.95%.
Summary statistics
In overround terms, those are approximately 5.78, 5.56 and 1.74 percentage points above 100% respectively.
What stands out
1. The average single-book market sat around 5% to 6% above 100%
The market-average book was remarkably consistent in this small sample. Nine of the 10 matches sat between 105.15% and 105.87%; Leeds v Everton was the highest at 106.02%.
2. One bookmaker varied more than the market average
Bet365 ranged from 104.33% on Nott'm Forest v Brentford to 107.50% on Aston Villa v Newcastle. That does not prove anything about long-run pricing, but it shows why a single headline figure such as “football margin is 5%” can hide meaningful match-to-match variation.
3. Price shopping changed the arithmetic materially
The best listed price for each outcome reduced the average book from roughly 105.5% to 101.7% in this sample. That does not mean one bookmaker offered a 101.74% book. The best-available figure combines prices from different bookmakers. It measures what happened when the strongest listed price was selected outcome by outcome.
Worked example: Liverpool v Bournemouth
Bet365's opening 1X2 prices were 1.30, 6.00 and 8.50.
Home: 1 ÷ 1.30 = 76.92%
Draw: 1 ÷ 6.00 = 16.67%
Away: 1 ÷ 8.50 = 11.76%
Total = 105.35%
The book therefore sat 5.35 percentage points above 100%. Using the maximum listed prices across the source file—1.34, 6.50 and 9.50—produced a combined book of only 100.54%.
Data source and reproducibility
The underlying match and odds data comes from Football-Data.co.uk, which publishes historical football results and bookmaker odds in CSV format. We used the 2025/26 English Premier League file (division code E0) and calculated the book percentages ourselves.
To make the work checkable, Betting Maths publishes the derived 10-row dataset used in this article. It includes the source odds and our calculated book percentages for the opening and closing snapshots.
Limitations
- This is one Premier League round: 10 matches, not a claim about every football market.
- The source's “average” and “maximum” fields depend on the bookmakers represented in that file at the time.
- The best-available book combines different bookmakers and should not be described as one bookmaker's margin.
- Overround is a pricing measure. It is not the same thing as realised bookmaker profit or a bettor's guaranteed expected loss.
- Prices can move over time; this article focuses on the opening snapshot. A separate analysis compares opening and closing books.
Why this matters
Overround is often taught with a made-up three-outcome example. That is useful for learning the formula, but real markets are more informative. This snapshot shows that the size of the book varied by match, that the bookmaker-specific figure differed from the market average, and that shopping across prices materially changed the combined implied probability.
The next step is to repeat this kind of analysis over larger samples and different market types, so Betting Maths can build a growing body of observed data rather than relying only on theoretical examples.
