Calculate the expected value of any bet from your odds and fair probability.
Arbitrage Calculator
Find guaranteed profit opportunities across two bookmakers.
$
ARB FOUND
Stake on Outcome 1
—
Stake on Outcome 2
—
Guaranteed Profit
—
ROI
—
Back & Lay Calculator
Calculate lay stakes for Betfair exchange hedging. Back at a bookmaker, lay on the exchange.
$
%
Lay Stake
—
Profit if Back Wins
—
Profit if Lay Wins
—
Betfair Liability
—
Bonus Bet Turnover Calculator
Convert bonus/free bets into guaranteed cash. Bonus bet stake is not returned — only profit.
$
%
Lay Stake
—
Guaranteed Profit
—
Retention %
—
Betfair Liability
—
No Vig / Fair Odds Calculator
Remove the bookmaker's margin to find true fair odds and probabilities.
Fair Odds 1
—
Fair Odds 2
—
Fair Odds 3
—
True Prob 1
—
True Prob 2
—
True Prob 3
—
Overround
—
Vig / Margin
—
Vig Calculator
See exactly how much the bookmaker is taking from both sides of a two-way market.
Bookmaker's Edge
—
Vig / Margin
—
Overround
—
Fair Odds 1
—
Fair Odds 2
—
Implied Prob 1
—
Implied Prob 2
—
True Prob 1
—
True Prob 2
—
Kelly Criterion Calculator
Determine optimal bet sizing based on your edge and bankroll.
%
$
+EV BET
Full Kelly %
—
Recommended Stake
—
Expected Value / Bet
—
Edge %
—
Conservative Sizing
Quarter Kelly
—
—
Half Kelly
—
—
Full Kelly
—
—
Expected Value Calculator
Determine whether a bet has positive expected value (+EV).
%
$
+EV BET
Expected Value
—
EV % per Bet
—
Break-even Probability
—
Your Edge
—
Odds Converter
Enter odds in any format — decimal (2.50), fractional (3/2), or American (+150 / -200).
Decimal
—
Fractional
—
American
—
Implied Probability
—
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
—
Profit if Original Wins
—
Profit if Hedge Wins
—
Guaranteed Profit
—
Expected value (EV) is the average amount a bet is worth if you could place it many times. A positive EV means the odds are in your favour over the long run. Enter the price, your estimate of the true win probability and your stake to see the EV.
How to use it
Enter the decimal odds on offer.
Enter your estimated fair win probability (from a no-vig line).
Enter your stake.
Read the expected value in dollars and as a percentage of stake.
Worked example. A $100 bet at 2.10 with a true win probability of 52% has EV = (0.52 x $110) minus (0.48 x $100) = +$9.20, or +9.2%. Positive EV, so it is a bet worth making even though it can still lose on the day.
EV is a long-run average, not a promise on any single bet, so variance is normal. Size positive-EV bets with the Kelly calculator and find them automatically with the DegenToPro +EV finder.
Frequently asked questions
What is a good EV percentage?
Sustainable +EV bets often sit in the 1% to 8% range. Much higher figures usually mean either a stale price or an overestimated probability, so sanity check your inputs.
Where do I get the fair probability?
Derive it from a sharp, no-vig market rather than the bookmaker you are betting with. The no-vig calculator turns a sharp price into a fair probability.
Does positive EV mean I will win the bet?
No. EV is the long-run average across many bets. A +EV bet can and often does lose on any single occasion. The edge only shows up over a large sample.