Your model's estimate of the true probability
Enter as +280, -110, etc.
How to interpret: Positive EV means this bet returns profit over infinite repetitions at your estimated probability. The book's implied probability vs your estimate is where edge lives.
$0.00
Expected Value per bet
Your Probability—
Book Implied Prob—
Edge—
Profit if Win—
Loss if Lose—
Enter values to calculate
Quick Reference Table
| American | Decimal | Implied% |
|---|---|---|
| +300 | 4.00 | 25.0% |
| +200 | 3.00 | 33.3% |
| +150 | 2.50 | 40.0% |
| +100 | 2.00 | 50.0% |
| -110 | 1.91 | 52.4% |
| -150 | 1.67 | 60.0% |
| -200 | 1.50 | 66.7% |
Half Kelly is recommended for most bettors. Full Kelly maximizes long-run growth but produces extreme variance — drawdowns of 50%+ are common even on +EV strategies. Half Kelly cuts variance by 75% at the cost of ~13% reduced growth rate.
$0
Optimal bet size
Kelly %—
Full Kelly—
Half Kelly—
Quarter Kelly—
Edge—
Enter values to calculate
The odds when you placed your bet
The odds when the game started
Why CLV matters more than results: A bettor who consistently beats the closing line by 3–5% will be profitable over thousands of bets, regardless of short-term win/loss. CLV is skill. Results are partly variance.
0.0%
Closing Line Value
Your Implied Prob—
Close Implied Prob—
CLV in $—
Annualized ROI (est.)—
Enter values to calculate
LEG 1
LEG 2
$0
Expected Value
$0
Potential Payout
0%
True Win Prob
0%
Book Implied
Add legs and calculate
The parlay trap: Each leg multiplies the EV disadvantage. A 3-leg parlay at −110 each requires all three legs to win AND creates 3× the vig drag. Parlays only have positive EV when every leg individually has positive EV — which is rare with book odds.
Enter the odds offered on your bet
How many bets to simulate at break-even
At −110 odds, you need to win 52.38% of bets to break even. That's the vig working against you. At +150, you only need 40% wins. This is why positive odds can have higher break-even on volume — less vig drag.
52.4%
Break-Even Win Rate
Implied Probability—
Vig (house edge)—
Wins needed (sim)—
Total risked (sim)—
EV per 100 bets at break-even$0.00
Enter odds to calculate
Profitable paths
Losing paths
Median path
Starting bankroll
0%
% Profitable
$0
Median Final
$0
Best Case
$0
Worst Case
0%
Ruin Risk
+$0
Theoretical EV
How to use the simulator: Set your estimated win rate, the odds you'll be betting at, bet size as % of bankroll, and number of simulations. Click Run — watch all paths render simultaneously. The gold median line is your most likely outcome. The spread of paths shows your variance risk. Hover over the canvas to see specific bankroll values.