SPORTS BETTING MATH
ILLUSTRATIVE COST MODEL

Bookmaker Overround: Comparison Method and Cost Model

Compare complete markets using dated quotes. This page has no verified 1win or Stake price dataset and does not rank their margins.

Topic illustration: Bookmaker Overround: Comparison Method and Cost Model
Conceptual illustration. Numerical assumptions and worked examples are explained in the text.
Overround and expected loss are different
Two-way odds 1.91 / 1.91. Loss assumes true probabilities 0.50 / 0.50.

Hypothetical Overround Cost Comparison

Scenario A uses your selected overround. Scenario B assumes 3.2% for illustration, not a partner rate. Costs use proportional de-vig probabilities.

Monthly Betting Volume ($) $3,000
Total turnover (sum of all stakes placed per month)
Scenario A Overround (%) 6.5%
4.0% 6.5% 10.0%
Scenario A Expected Cost: $183.10 per month
Scenario B: Assumed 3.2%: $93.02 per month
Annual Modelled Cost Difference
+$1,080.90
+$90.08 per month

Expected cost = turnover × m/(1+m) under proportional de-vig. Actual bettor EV needs outcome probabilities and selection. This comparison is not a profit forecast.

Partner Margin Evidence Status

Dated, matched partner quotes have not been supplied for this page. A league ranking or exact partner margin cannot be supported.

Quote Set Market 1win Stake Other Operator A Other Operator B
Comparable quotes required 1X2 Not measured Not measured Not measured Not measured

How to Make a Comparable Quote Set

1win: Record Current Quotes

Not measured

Use prices from one complete market and record time, event and settlement rules. No verified 1win quote set is provided here.

Open 1win Sports →

Stake: Record Current Quotes

Not measured

Record the same event, market, time and settlement rules before comparing. No verified Stake quote set is provided here.

Open Stake →

Check Settlement Rules

Not measured

Pushes, voids, overtime and outcome definitions must match. A different settlement model changes the comparison.

Include Execution Costs

Not measured

Use available prices and account for commissions, stake limits and monetary rounding. Overround alone does not establish your expected value.

Methodology & Margin Mechanics

For mutually exclusive, exhaustive outcomes, overround is the excess of the sum of inverse decimal odds above one. It is not the fraction of each stake lost.

Overround = ∑ (1 / O_i) - 1.00

Illustration: turnover $10,000 with assumed overrounds 6% and 3.2% gives expected costs $566.04 and $310.08, a $255.96 difference. These assumptions are not measured bookmaker prices.

Frequently Asked Questions (FAQ)

What is a bookmaker margin (overround)?

Overround m = Σ(1/O_i) - 1 for a complete market. Under proportional de-vig, expected loss is m/(1+m), not m.

What is considered a "good" or "low" margin in sports betting?

Compare lower overround only for matched markets and times. It does not establish a profitable selection or guaranteed execution.

How does margin affect a bettor's expected value (+EV)?

For one outcome, net EV per unit is p × O - 1. Estimating p and its uncertainty is necessary; overround alone is insufficient.

Why do margins differ between the Premier League and minor leagues?

Use dated observations rather than assuming one fixed margin for every league or operator.

How do 1win and Stake compare on sports betting margins?

No verified dated partner quotes support a ranking here. Both operators remain available through the account links.