Measure the bookmaker's built-in margin on any market.
Arbitrage Calculator
Find guaranteed profit opportunities across two bookmakers.
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ARB FOUND
Stake on Outcome 1
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Stake on Outcome 2
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Guaranteed Profit
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ROI
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Back & Lay Calculator
Calculate lay stakes for Betfair exchange hedging. Back at a bookmaker, lay on the exchange.
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%
Lay Stake
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Profit if Back Wins
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Profit if Lay Wins
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Betfair Liability
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Bonus Bet Turnover Calculator
Convert bonus/free bets into guaranteed cash. Bonus bet stake is not returned — only profit.
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%
Lay Stake
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Guaranteed Profit
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Retention %
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Betfair Liability
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No Vig / Fair Odds Calculator
Remove the bookmaker's margin to find true fair odds and probabilities.
Fair Odds 1
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Fair Odds 2
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Fair Odds 3
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True Prob 1
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True Prob 2
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True Prob 3
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Overround
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Vig / Margin
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Vig Calculator
See exactly how much the bookmaker is taking from both sides of a two-way market.
Bookmaker's Edge
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Vig / Margin
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Overround
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Fair Odds 1
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Fair Odds 2
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Implied Prob 1
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Implied Prob 2
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True Prob 1
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True Prob 2
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Kelly Criterion Calculator
Determine optimal bet sizing based on your edge and bankroll.
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$
+EV BET
Full Kelly %
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Recommended Stake
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Expected Value / Bet
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Edge %
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Conservative Sizing
Quarter Kelly
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Half Kelly
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Full Kelly
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Expected Value Calculator
Determine whether a bet has positive expected value (+EV).
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$
+EV BET
Expected Value
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EV % per Bet
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Break-even Probability
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Your Edge
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Odds Converter
Enter odds in any format — decimal (2.50), fractional (3/2), or American (+150 / -200).
Decimal
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Fractional
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American
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Implied Probability
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Common Odds Reference
Decimal
Fractional
American
Implied Prob.
1.50
1/2
-200
66.67%
1.80
4/5
-125
55.56%
1.91
10/11
-110
52.36%
2.00
1/1
+100
50.00%
2.50
3/2
+150
40.00%
3.00
2/1
+200
33.33%
4.00
3/1
+300
25.00%
5.00
4/1
+400
20.00%
10.00
9/1
+900
10.00%
21.00
20/1
+2000
4.76%
Hedge / Cash Out Calculator
Lock in a guaranteed profit on an existing bet by hedging the opposite outcome.
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Hedge Stake
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Profit if Original Wins
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Profit if Hedge Wins
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Guaranteed Profit
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The vig (also called juice, margin or overround) is the edge a bookmaker bakes into its prices. This calculator adds up the implied probabilities of a market and shows how far above 100% they sit, which is the margin you are paying.
How to use it
Enter the odds for each outcome of the market.
The calculator converts each to an implied probability and sums them.
Read the total margin as a percentage above 100%.
Worked example. Odds of 1.90 / 1.90 imply 52.63% + 52.63% = 105.26%, a vig of 5.26%. A tighter market priced 1.95 / 1.95 carries only about 2.6% margin, so it is better value.
Lower vig means a better price and more of your money working for you. Comparing margins across books is one reason odds comparison matters. To strip the margin out entirely use the no-vig calculator.
Frequently asked questions
What is a good vig / margin?
Lower is better for you. Sharp bookmakers and exchanges run margins of 2% or less on major markets, while softer books and exotic markets can exceed 10%.
Is vig the same as the bookmaker's profit?
It is the theoretical margin built into the prices. Actual profit depends on how balanced the bookmaker's liabilities are, but a higher vig means a worse price for the bettor.
How do I avoid paying too much vig?
Line shop across bookmakers and take the highest price for each outcome, and favour low-margin markets. Compare live prices with an odds comparison tool.