Work out your exact lay stake and locked-in profit for matched betting.
Arbitrage Calculator
Find guaranteed profit opportunities across two bookmakers.
$
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.
$
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 back/lay calculator is the core matched betting tool. You back a selection at a bookmaker and lay the same selection on an exchange, and the calculator tells you exactly how much to lay so your profit is the same whether the bet wins or loses.
How to use it
Enter your back odds and back stake at the bookmaker.
Enter the lay odds available on the exchange.
Set the exchange commission (Betfair default is 5%).
Read the lay stake to place, the liability you need free in your exchange wallet, and your profit if the back or the lay wins.
Worked example. A $50 qualifying bet at back odds 2.00, lay odds 2.04, 5% commission needs a lay stake of about $49. You lose only a few cents on the qualifier, which is the small cost of unlocking a much larger bonus bet.
Toggle the mode when you are working a stake-not-returned bonus bet rather than a qualifier. For the full method see the matched betting guide.
Frequently asked questions
What is the difference between a qualifying bet and a bonus bet?
A qualifying bet uses your own cash and aims to break even while you unlock an offer. A bonus (stake-not-returned) bet uses the free credit and aims to convert as much of it to cash as possible. Set the calculator to the matching mode.
Do I need Betfair to matched bet in Australia?
You can lay on the Betfair Exchange, or use the two-bookmaker back-to-back method where you back opposing outcomes at two bookmakers. The calculator's lay mode assumes an exchange.
Why is my lay stake different from my back stake?
Because the lay odds and commission differ from the back odds. The calculator balances the two sides so your outcome is the same either way, which almost never means equal stakes.