The Bet Better Margin Index
What a bet actually costs, measured every day
The bookmaker's margin — the overround built into a set of prices — is the price you pay
to place a bet. It is rarely published. This index measures it directly from a live
multi-book odds archive and updates daily.
Updated 2026-09-29 · 91 days in the series
5.12%
Head-to-head margin
(the headline index)
7.80%
Most expensive market type
Player props
2,474,831
Markets measured
on this day alone
66
Bookmakers
in the sample
On a $100 bet, a 5.12% margin is about
$5.12 of built-in cost before the result is known.
Margin by market type
| Market type |
Mean margin |
Median |
Markets |
Books |
| Handicaps / spreads |
5.05% |
4.76% |
432,848 |
51 |
| Head-to-head (two-way) |
5.12% |
4.91% |
486,791 |
66 |
| Totals (over / under) |
5.99% |
5.77% |
752,117 |
56 |
| Other markets |
6.49% |
6.49% |
3,045 |
35 |
| Match result (three-way) |
7.64% |
7.40% |
733,663 |
57 |
| Player props |
7.80% |
7.28% |
66,367 |
22 |
Read it as a price ladder: the simpler the bet, the less it costs you. Player props
carry the widest margins of any market type measured here.
Which sports cost you the least
The same head-to-head margin, split by sport on the latest day measured. A lower
number means the bookmakers keep less of every dollar bet on that sport.
| Sport |
Margin |
Cost on $100 |
Markets |
Books |
| NFL |
4.35% |
$4.35 |
40,953 |
21 |
| College football |
4.57% |
$4.57 |
116,510 |
18 |
| MLB |
4.66% |
$4.66 |
25,588 |
51 |
| NHL |
4.74% |
$4.74 |
48,362 |
26 |
| WNBA |
4.79% |
$4.79 |
13,687 |
27 |
| UFC / MMA |
5.06% |
$5.06 |
40,777 |
22 |
| NRL |
5.10% |
$5.10 |
2,304 |
18 |
| NBA |
5.79% |
$5.79 |
84,591 |
37 |
Head-to-head markets only, sports with at least 5 measured markets on the day.
Want the margin stripped out of a specific set of prices? The
no-vig calculator
does it for any two or three-way market.
Head-to-head margin, last 30 days
From 2026-08-31 to 2026-09-29.
Method
For every bookmaker's quote on every market, we sum the implied probabilities of all
outcomes. A fair market sums to 1.00; anything above that is the margin. We record
each quote as a separate observation, so a market quoted by 40 bookmakers contributes
40 measurements rather than one average.
Handicap markets are paired on the absolute value of the line, because the two sides
carry opposite numbers. Head-to-head markets may have two or three outcomes; every
other market type is measured two-way. Observations that resolve outside 0–30% are
mispaired or stale quotes and are excluded —
on the latest day that filter removed at most
0.94% of observations in any market type.
The index reports aggregates only. It publishes no odds, no prices and no bookmaker
identities, so it can be reused freely without redistributing licensed market data.
Use the data
The full daily series is available as CSV:
betbetter-margin-index.csv — released under CC BY 4.0.
Cite this index
Glush, E. (2026). The Bet Better Margin Index: daily measured bookmaker
margins across market types. Bet Better. https://betbetter.world/studies/margin-index