Bookmaker Margin Calculator
Bookmakers don't offer fair odds — they build in a margin (also called the vig, juice or overround) so the implied probabilities of a market add up to more than 100%. This free margin calculator shows exactly how much a book is charging on any market.
Enter the odds for every outcome. It sums the implied probabilities (1/odds) and shows the margin above 100% — the lower the number, the sharper the book. Comparing margins is a quick way to find where you get the best prices.
Bookmaker margin (vig)
3.17%
Overround (sum of implied %)
103.17%
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Frequently asked questions
How is bookmaker margin calculated?
Add up 1/odds for every outcome to get the overround, then subtract 100%. For a two-way market at 1.90 / 1.90, that's 0.526 + 0.526 = 105.3%, so the margin is 5.3%.
What is a good margin?
Sharp books like Pinnacle run 2–3% on main markets; soft books are often 5–8% or more, and niche markets can exceed 10%. Lower margin means better odds and less edge you have to overcome.
Margin vs overround — what's the difference?
The overround is the sum of implied probabilities (e.g. 105%); the margin is how much that exceeds 100% (5%). They describe the same thing.
Related reading
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<p style="font:13px/1.4 system-ui,sans-serif;margin:8px 0 0">Free <a href="https://profitbetting.io/tools/margin-calculator">Bookmaker Margin Calculator</a> by ProfitBetting</p>