Bookmaker Margin Panel: Daily Measured Betting Margins Across 22 Leagues and Player-Prop Markets

# Bookmaker Margin Panel — daily measured betting margins across 22 leagues and 3 market types A daily panel of **measured bookmaker margins (overround/vigorish)** across head-to-head, spread and totals markets: one row per day × league × region × market type, aggregated from over 4 million individually recorded odds observations (2.7 million cleaned markets). To our knowledge this is the only openly published bookmaker margin panel. It quantifies the *price* of sports betting — the amount by which a market's implied probabilities exceed 100% — across operators, sports and time. | | | |---|---| | **Files** | Main panel: 3,494 cells (day × league × region × market type × time-to-start) · Props panel: 1,148 cells | | **Underlying observations** | 2,002,681 cleaned main markets + 699,733 two-sided player-prop markets | | **Bookmakers aggregated** | 52 (not identified individually — see Limitations; exchanges excluded) | | **Leagues** | 22 competition keys across 15 sports, including 9 soccer leagues | | **Market types** | head-to-head (2- and 3-way), spread, total | | **Period** | 29 June – 2 August 2026, 35 days (collection continues; quarterly updates planned) | | **Licence** | CC BY 4.0 | ## Columns | Column | Meaning | |---|---| | `snap_date` | Observation date (UTC) | | `sport` | League/competition key, e.g. `baseball_mlb`, `soccer_epl` | | `region` | `au`, `us` or `offshore_intl` — the licensing region of the operators aggregated in the cell | | `market_type` | `h2h`, `spread` or `total` (main panel); specific prop market key in the props file | | `time_to_start` | Hours from observation to scheduled start, bucketed (under 6h to over 7 days) — main panel | | `outcomes` | Number of priced outcomes (2, or 3 for soccer-style h2h with the draw) | | `mean_margin_pct` | Mean margin that day: sum of the outcomes' implied probabilities minus 100, in percent | | `n_markets` | Number of distinct market observations in the cell (cells with fewer than 10 are excluded) | | `n_bookmakers` | Number of distinct operators aggregated in the cell | ## Method For every pre-match market observation, all priced outcomes were converted to implied probabilities (1 ÷ decimal odds) and summed; the excess over 100% is the margin. Two-way and three-way markets are kept in separate cells because their margins are not comparable. Excluded: in-play observations, implausible margins (below 0%, or above 20% two-way / 35% three-way — suspended or near-settled prices), and betting exchanges. Full methodology: https://betbetter.world/studies/bookmaker-margins ## Headline findings from this panel - **Player props average a 7.93% margin — 66% more than main head-to-head markets (4.77%)**. To our knowledge this is the first public measurement of prop-market margins (699,733 two-sided prop markets, MLB/NHL/soccer/basketball prop families). - The market-type price ladder: h2h **4.77%** → spreads **4.90%** → totals **5.45%** → three-way soccer h2h **7.67%** → player props **7.93%**. - **Margin has a term structure**: it peaks 1–3 days before the start (5.23%) and compresses to 4.71% in the final six hours — betting early costs measurably more. - **Australian-licensed bookmakers average 5.25%, US-licensed 4.72%, offshore/international 4.55%** — Australians pay roughly 11% more margin than Americans for equivalent bets. - Individual operators are not identified in these files; operator-level statistics (a 3.16% to 5.78% spread between the cheapest and dearest bookmaker) are published in the accompanying study: https://betbetter.world/studies/bookmaker-margins ## Limitations One month of collection (a longer panel accumulates with each planned update). Individual bookmakers are deliberately not identified in the files: cells aggregate across all operators in a region (n_bookmakers reports how many), so no operator's prices or price patterns are recoverable — the files are irreversible statistics, not a data feed in any form. Head-to-head is the tightest market type bookmakers offer; margins on multis and player props are materially higher, so these figures are a floor for the cost of betting generally. No individual odds, prices or market observations are included — both files are aggregate statistics derived from a licensed feed that does not permit redistribution of the underlying prices. ## Licence and citation CC BY 4.0 — free to use, including commercially, with attribution. > Bet Better (2026). *Bookmaker Margin Panel: daily measured betting margins across 22 leagues, > three market types and player-prop markets.* https://betbetter.world/studies/bookmaker-margins Maintained by [Bet Better](https://betbetter.world), which also publishes a [free sports model API](https://betbetter.world/api/) and an [open AFL dataset](https://doi.org/10.5281/zenodo.21612783). > This dataset contains no odds, no prices and no wagering data — aggregate statistics only. 18+. > Most people lose money gambling. If gambling is causing you harm: gamblinghelponline.org.au.