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Monte Carlo trading simulator
Expectancy tells you the average. It does not tell you how wide the spread around that average is, or how bad the worst stretch gets on the way there. This runs the same numbers a thousand times over and shows you the whole distribution.
These calculators do arithmetic on numbers you enter. They do not produce recommendations, do not connect to any market feed, and do not know what any instrument is worth — that is never advice, and it is not a substitute for your own judgement or a licensed professional's.
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to use the monte carlo trading simulator — and the other 6: Position Size, Risk : Reward, Margin & Leverage, Drawdown, Options Payoff, Delta-Adjusted Sizing
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The account is free and takes a moment. Whatever you type into the calculators afterwards still stays in your browser — it is never sent to a server, stored, or logged.
How this is calculated
No hidden model and nothing fitted to data. Every figure on this page comes out of these lines, applied to the numbers you typed.
expectancy (R) = win% x avg win - loss% x avg loss
risk per trade = balance x risk % (compounding)
on a win = balance + risk x avg win
on a loss = balance - risk x avg loss
repeat for n trades, x 1,000 runs
report = median, 5th / 95th percentile, worst drawdownThe other three
Position Size
How many units does my risk budget actually buy?
Risk : Reward
What win rate does this payoff need to break even?
Margin & Leverage
How far can this move against me before maintenance?
Drawdown
What does this decline demand back before it is undone?
Options Payoff
Where does this position break even, and what is the worst case?
Delta-Adjusted Sizing
How many contracts does my risk budget actually allow?
Frequently asked questions
- What does a Monte Carlo simulation tell me that expectancy does not?
- Expectancy is a single average. Two systems with identical expectancy can produce very different experiences - one grinding steadily, the other swinging through long losing runs to reach the same place. A simulation re-orders the same wins and losses many times and shows the range of paths those numbers permit, including the unpleasant ones.
- What assumptions does this make?
- Three, and all three are simplifications. Every trade is independent, so no streakiness or regime change is modelled. The win rate and the average win and loss stay constant for the whole run. And every trade risks the same percentage of the balance at that moment. Real markets satisfy none of these, which means the true spread of outcomes is wider than the one shown, not narrower.
- Is this a prediction of my results?
- No. It is a simulation of the numbers you entered and nothing else. If those numbers came from a small sample, or from a period that does not resemble the next one, the distribution describes the assumption rather than the future. Nothing here is a forecast, a recommendation or a statement about any market or security.
- Why does it not tell me what risk percentage to use?
- Because that would be position-sizing advice, and this page is not qualified to give any. Formulas that output an optimal bet size - the Kelly criterion being the best known - produce a number that reads exactly like an instruction, and a reader who follows it has been advised by a calculator. You set the risk; the tool shows the consequence of the setting.
- Why do I get the same results each time I run it?
- The random draw is seeded, so a given set of inputs always produces the same distribution. That is deliberate: if the draw changed on every keystroke, comparing one risk percentage against another would measure the noise rather than the change you made. Change the seed to see a different set of paths.
- Are my inputs sent anywhere?
- No. All thousand runs execute in your browser as JavaScript on this page. Your win rate, account size and risk percentage are never transmitted, never stored and never logged. A free account unlocks the simulator; it does not send anyone your numbers.
⚠ Important disclaimer
These calculators are provided strictly for educational and informational purposes. They perform arithmetic on figures you enter. Nothing on these pages is financial, investment, trading, legal or tax advice, nor a recommendation to buy, sell or hold any security, derivative, commodity or cryptocurrency.
The creator is not a registered investment adviser, research analyst or broker with the SEC, FINRA, CFTC, NFA, any U.S. state securities regulator, or SEBI (as an Investment Adviser or Research Analyst). Trading involves substantial risk of loss — you can lose some or all of your capital, and with leveraged instruments you can lose more than you deposit.
Contract specifications, lot sizes and margin rates shown here are seeded from published standards, are editable, and may be out of date or wrong for your broker. Exchanges revise lot sizes and margin requirements, and brokers routinely impose more than the regulatory minimum. Verify every figure against your own broker before acting on it. These tools carry no warranty of any kind and may contain errors.
You are solely responsible for your own decisions. Read the full legal disclaimer →