Free tool
Kelly Criterion & Value Calculator
Enter your own estimated win probability and the odds on offer. This tells you the market's implied probability, your edge, and what a full or fractional Kelly stake would be — the same math behind every ServedBets pick.
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How this is calculated, exactly
Implied probability:1 ÷ decimal odds. What the market is pricing the outcome at, margin included — seethe full breakdown.
Edge: your estimate minus the implied probability. Positive means you think the true chance is higher than the price suggests.
Full Kelly stake uses the standard formula, with b as the net odds (decimal odds − 1) and p as your probability:
f = (b·p − (1 − p)) / b
This is the fraction of your bankroll that maximizes long-run growthif your probability estimate is exactly right. It's provably optimal under that condition — and provably punishing when the estimate is off, because it stakes hardest on exactly the bets where your edge (and any error in it) is largest.
Suggested stake is the full Kelly fraction multiplied by whatever fraction you pick above (a quarter by default). Real quarter-Kelly still lost to flat staking on our own tracked picks — seewhy, and why we default to flat 1-unit stakes ourselves.
This calculator does not know anything about tennis — it only does the math on the numbers you give it. Our own probability estimates come from the model described on the Methodology page. Want to see the realistic range of outcomes over many bets instead of a single one? Try theVariance & Bankroll Calculator.
Want the probability estimate too, not just the math?
We publish our own model's win probability and edge for every tennis pick in the Discord, live.