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Kelly Criterion Calculator

Compute the optimal fraction of your bankroll to stake from your win probability and win/loss ratio, with half and quarter Kelly.

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Kelly Criterion Calculator is free to use as often as you like, directly from this page. You will find it under Investing & markets, with Capital Gains Yield Calculator and Currency converter for the neighbouring cases.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.
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Frequently asked questions

What is Kelly Criterion Calculator?

Compute the optimal fraction of your bankroll to stake from your win probability and win/loss ratio, with half and quarter Kelly.

When would I actually use this?

Comparing two investments that pay at different times, deciding whether a project clears its cost of capital, and sanity-checking a valuation someone else produced.

What is the most common mistake?

Trusting a valuation without asking what share of it comes from the terminal value. Past 70%, the answer is an assumption about the distant future dressed up as a calculation.

How is Kelly Criterion Calculator different from Capital Gains Yield Calculator?

They sit next to each other but answer different questions. Capital Gains Yield Calculator: compute the capital gains yield from the purchase and current price, with dividend yield, total return and the annualised equivalent. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Currency converter is the closest one after this: Convert the euro and 29 other currencies at European Central Bank reference rates, dated and updated each working day, with cross rates and a 90-day chart.

What else is worth having open alongside it?

Dividend Payout Ratio Calculator and Dividend Reinvestment (DRIP) Calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

Discounting, IRR and payback are defined identically everywhere, so the arithmetic is not in dispute — the assumptions you feed it are. Change the discount rate by a point and re-read the answer.

Further reading

All guides →
ExplainerRisk/Reward Ratio Explained: The Win Rate Each Ratio RequiresA 1:3 ratio does not make you right more often — it lets you be wrong three times out of four and still break even. Here is the inversion, a table of ratio against required win rate, and what costs do to both.GuidePosition Sizing: What the 1 Percent Rule Actually ConstrainsThe rule caps the loss, not the position. Here is the formula, a worked example, and what a run of ten losses costs at 1 percent versus 2 percent.ExplainerPrice Return, Total Return and Yield Are Three Different NumbersThe index quoted in the news is almost always a price index. At 5 percent price growth and a 2.5 percent reinvested yield, 30 years turn $10,000 into $43,219 on price and $90,656 on total return — the price measure misses 58.8 percent of the gain.ExplainerDividend Reinvestment: What Actually Drives the DifferenceReinvesting a 3 percent yield for 30 years turns 100 shares into 242.7 and multiplies the final position by exactly that factor: $32,434 becomes $78,726. Tax at 30 percent on each dividend costs $18,223 of it — nearly two and a half times the tax actually paid.ExplainerTax-Equivalent Yield: Comparing a Tax-Free Bond With a Taxable OneTaxable-equivalent yield = tax-free yield ÷ (1 − marginal rate). A 3.00 percent tax-free yield is worth 3.85 percent at a 22 percent marginal rate and 5.07 percent at 40.8 percent. The trap is that it is the marginal rate, surtaxes and social levies included — leaving them out costs 0.85 points of yield.ExplainerPaying Off a Loan Early: What Actually ChangesAn overpayment earns exactly the loan's rate, risk-free and after tax. On $200,000 at 5.00 percent over 25 years, $20,000 paid at the start saves $42,092 of interest; the same sum at year 16 saves $11,088; applied to the payment instead of the term it saves only $15,075.
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