Convert between decimal, fractional, American odds and implied probability.
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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Different bookmakers and countries quote odds in different formats. This converter translates any price between decimal, fractional and American (moneyline) formats and shows the implied probability, so you can compare like for like.
How to use it
Type a price into any one of the format boxes.
The other formats update instantly.
Read the implied probability alongside them.
Worked example. Decimal 2.50 equals fractional 3/2 equals American +150, and implies a 40% probability. Decimal 1.50 equals 1/2 equals American -200, implying 66.7%.
Implied probability is the bookmaker's price expressed as a percentage before margin. To see the fair probability with the margin removed, use the no-vig calculator. Australian books quote decimal odds by default.
Frequently asked questions
What is implied probability?
It is the odds expressed as a percentage chance. For decimal odds it is 1 divided by the odds. It includes the bookmaker's margin, so it slightly overstates the true chance.
How do I convert decimal to American odds?
For decimal odds of 2.00 or higher, American = (decimal - 1) x 100. Below 2.00, American = -100 / (decimal - 1). The converter does this for you instantly.
Which odds format is best?
It is a personal preference. Decimal is the standard in Australia and the easiest for calculating returns and EV. The converter lets you work in whichever you prefer.