Learn / Kelly Criterion
How big should this bet be? The Kelly criterion for sports betting.
The math that converts a probability edge into a bankroll fraction. NuroPicks ships a fractional Kelly recommendation on every Pro and Elite pick.
Plain-English answer
The Kelly criterion is a bet-sizing formula that picks the stake that maximizes long-run bankroll growth given a known edge. The full formula is f = (bp minus q) divided by b, where b is the decimal odds minus one, p is your probability of winning, and q is one minus p. A 55% read on a plus 100 spread gives f equals 0.10, meaning the math says risk 10 percent of bankroll. Real bettors run quarter or half Kelly because edge estimates are noisy and full Kelly accepts wild drawdowns. NuroPicks ships per-pick fractional Kelly recommendations on every Pro and Elite call, and you can run any line through the slash command /kelly inside the Discord server.
The formula
f = (b * p - q) / b
- f is the fraction of bankroll to risk on this bet.
- b is the decimal odds minus one (so plus 100 American odds equals 1.0).
- p is your estimated probability of winning.
- q is the probability of losing (1 minus p).
If f comes out negative, the bet has no edge and Kelly says do not bet. If f comes out above 0.20 you are almost certainly overestimating your edge.
Worked example
Tuesday 9:30 PM ET. Lakers at Nuggets. NuroPicks model output: Lakers minus 4.5 at plus 100, estimated win probability 55 percent.
Plug in the values:
- b = 1.0 (plus 100 decimal is 2.0, minus 1)
- p = 0.55
- q = 0.45
- f = (1.0 * 0.55 - 0.45) / 1.0 = 0.10
Full Kelly says risk 10 percent of bankroll. On a 1,000 dollar bankroll that is a 100 dollar stake. Most disciplined bettors would not actually bet 100 dollars here. They would size to quarter Kelly at 25 dollars or half Kelly at 50 dollars to absorb the edge-estimate noise.
Run any pick through /kelly in the Discord server and the bot will return the full, half, and quarter Kelly stakes against your tracked bankroll.
Why fractional Kelly is the only sane choice
- Edge estimates are noisy. A 55 percent read could really be 52 percent. Full Kelly with overestimated edge is the fastest known way to blow up a bankroll. Fractional Kelly cuts the drawdown risk in half or more.
- Variance is brutal at full size. Full Kelly accepts a roughly 33 percent expected drawdown over the lifetime of the bankroll. Half Kelly cuts that to about 17 percent for slightly less than half the long-run growth rate.
- Most published edges round down, not up. Books move on sharp money fast. By the time you place the bet your real probability is often 1 to 2 points lower than the model estimate.
- NuroPicks defaults to quarter Kelly in stake recommendations. You can override per pick, but the published number on every receipt is the quarter-Kelly stake to keep variance survivable.
Use it live
Every NuroPicks Pro and Elite pick ships with a fractional Kelly stake recommendation against your tracked bankroll. Pair this with CLV and SHAP for the full transparency stack.
21+ only. Not financial advice. 1-800-GAMBLER.
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