For First Responders · Kelly Criterion
Kelly Criterion for an emergency fund
Built for first responders planning or training for real incidents. Run fast what-if scenarios for response planning and training — no software to install in the field. Simulate an emergency fund live below — adjust the inputs and watch it respond, right in your browser.
Kelly CriterionLive
the mathematically optimal bet size
Controls
Presets
The Kelly criterion gives the bet fraction that maximizes long-run growth: f = (bp − q)/b. Bet less and you grow slower; bet more and volatility eventually ruins you. Many practitioners use a fraction of Kelly to tame the swings. Educational tool, not financial advice.
Data Inspector
Kelly fraction10.0%
Edge (bp − q)0.100
Half-Kelly (safer)5.0%
Governing equation
Reading this result: Kelly stakes 10.0% of your bankroll per bet — the fraction that maximizes long-run growth; betting more raises volatility without raising growth, and eventually courts ruin.
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Frequently asked questions
- Is this good for first responders?
- Yes — this version of "Kelly Criterion for an emergency fund" is framed for first responders planning or training for real incidents. Run fast what-if scenarios for response planning and training — no software to install in the field.
- Do I need to install anything?
- No. It runs in any modern browser, free, with no account required.