About ExpectancyLab
What this site is
ExpectancyLab is a free set of tools and guides for understanding the mathematics of trading risk. The calculator shows how win rate, risk-to-reward ratio, risk per trade and the number of trades combine into expected results, a probability distribution of outcomes, and a Monte Carlo simulation of 1,000 possible sequences.
Why it exists
Most trading mistakes are not about entries. They come from not knowing what a strategy’s numbers really imply: how many losses in a row to expect, how deep a drawdown can get, and how a risk setting that looks small can become dangerous. The tools and guides here are meant to make those numbers visible before real money is involved.
How the calculations work
- Expectancy: win rate × reward-to-risk − loss rate, measured in R.
- Distribution: a binomial model that assumes each trade is independent with the same win probability.
- Monte Carlo: 1,000 random sequences generated from your inputs, in your browser.
- Privacy: the numbers you type are processed in your browser and are not sent to a server.
Limits
The models ignore spreads, slippage, commissions, changing market conditions and the fact that real win rates are estimates. They are for learning and stress-testing assumptions, not for predicting results. ExpectancyLab does not provide financial advice, trade signals or managed accounts. Please read the Terms of Service.
Get in touch
Found a mistake in a calculation or a guide, or want a topic covered? Use the Contact page.