ProTrading · Simulator
Kelly Criterion Calculator
The mathematically optimal bet size.
Assumptions
Full Kelly
25%
Half Kelly
13%
Edge
Positive
| Sizing | Fraction of Capital |
|---|---|
| Full Kelly | 25% |
| Half Kelly (recommended) | 13% |
| Quarter Kelly (conservative) | 6% |
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Built by The Crimson Bench · Educational model, not financial advice
About the Kelly Criterion Calculator
Enter your win probability and win/loss ratio to get the Kelly-optimal fraction of capital to risk — and the safer half-Kelly.
It's built for directional planning: change any assumption and watch the whole projection move, the way a seasoned operator pressure-tests a plan before committing capital. Everything is computed live in your browser — nothing is sent anywhere.
How the Kelly Criterion Calculator Works
The model takes 2 assumptions and returns 3 headline metrics plus a full breakdown. Here is exactly what goes in and what comes out — no black box.
The Inputs
| Assumption | Example value |
|---|---|
| Win probability | 55% |
| Win / loss size ratio | 1.5 |
Worked Example
Every figure below is produced by the live model using the example assumptions above. Change any input in the simulator to see your own numbers.
Full Kelly
25%
Half Kelly
13%
Edge
Positive
| Sizing | Fraction of Capital |
|---|---|
| Full Kelly | 25% |
| Half Kelly (recommended) | 13% |
| Quarter Kelly (conservative) | 6% |
The Operator's Read
Full Kelly maximizes long-run growth but is wild — most practitioners use half-Kelly to cut volatility for nearly the same growth. Never size above full Kelly; it guarantees eventual ruin. Educational only.
Assumptions & Limitations
- •The model is deterministic: it projects your inputs forward with clear arithmetic, not a Monte-Carlo or probabilistic forecast. It shows one scenario at a time — run several to bracket a range.
- •Defaults are illustrative benchmarks, not your business. Replace every field with your real numbers before drawing conclusions.
- •It abstracts away taxes, financing, seasonality, and one-off events unless a field explicitly captures them. Treat the output as a directional estimate.
- •This is an educational tool, not financial, investment, tax, or legal advice. Validate real decisions with a qualified professional.
Frequently Asked Questions
What does the Kelly Criterion Calculator calculate?
Enter your win probability and win/loss ratio to get the Kelly-optimal fraction of capital to risk — and the safer half-Kelly. It takes 2 assumptions — Win probability, Win / loss size ratio — and returns Full Kelly, Half Kelly, Edge, along with a full projection table you can export.
How do I use the Kelly Criterion Calculator?
Enter your own figures in the input fields above — Win probability, Win / loss size ratio, and the rest. The model recalculates instantly and shows the resulting Full Kelly and full breakdown. No sign-up needed to run it.
Is the Kelly Criterion Calculator free?
Yes — you can run the simulator and see the headline results for free. Toolkit Pro unlocks the full projection table, Excel/PDF export, saved scenarios, and AI analysis: $180/mo, $1,728/yr, or unlock any 3 simulators for $20.
What's the difference between this and a free calculator?
A calculator answers one question. This simulator models the full picture — multiple linked assumptions, a projection table, and scenario comparison — the way an operator would build it in a spreadsheet, but instantly.
Who built the Kelly Criterion Calculator?
The Crimson Bench's Ivy League-educated operators — the same people we deploy into C-suites. This is the self-serve version of a model they'd build inside a live engagement.
Is this financial advice?
No. The Kelly Criterion Calculator is an educational modeling tool for directional planning — not financial, investment, tax, or legal advice. Validate any real decision with a qualified professional.
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The Crimson Bench · Est. 2002 · Founded in New York City
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