Margin Calc
Two-way market margin (overround) and implied chances.
How to Use This Calculator
- Pick your odds format (Decimal, Fractional, or American)
- Punch in the odds for both outcomes
- If you like, add a stake to preview the potential payouts
- Read off the bookmaker margin and the implied probabilities
Formula
Implied Probability = 1 / Decimal Odds
Bookmaker Margin (Overround) = (1 / Odds₁) + (1 / Odds₂) − 1
Payout = Stake × Decimal Odds
Margins below 5% are considered competitive; above 10% are typical of recreational books or low-liquidity markets.
Frequently Asked Questions
What is bookmaker margin?
Margin — also called overround or vigorish — is the percentage by which the implied probabilities of every outcome add up beyond 100%. It’s the bookmaker’s expected take when liability is balanced. A 5% margin means they expect to pocket $5 of every $100 staked over time.
How is the margin calculator different from the hold calculator?
Both measure the same thing. This one is hands-on: enter your stake and see exactly what each outcome pays. The hold calculator leans analytical, spotlighting fair (no-vig) odds so you can stack bookmakers side by side.
Which bookmakers run the lowest margins?
Sharp Asian books (Pinnacle, Sbobet) have historically operated at 2-3% on top markets. European recreational books usually sit at 5-8%. Promotional or niche markets can blow past 15%.
Why does margin matter for long-term profit?
Margin is the headwind on every single bet. To break even at a 5% margin you have to win above the implied break-even rate. Lower-margin books simply make finding value bets mechanically easier.