Trading Probability Simulator

What this simulator is useful for

This tool is not trying to predict the next trade. It shows how a trading edge can feel over a sample of outcomes when wins and losses arrive in random order.

• Estimate how noisy a win rate can look over short samples.
• See losing streaks without assuming the system is broken.
• Connect reward/risk, expectancy and drawdown in one view.

How to use the trading probability simulator

Start with the probability settings only. Choose a win rate, choose the average reward/risk, run a sample and look at the observed win rate, losing streak and equity curve.

If you want to model money, enter risk per trade and choose an account model. Personal accounts use manual withdrawals. Prop firm style accounts add drawdown limits, withdrawal thresholds, optional trailing drawdown and optional auto-withdraw rules.

Choose the risk mode that matches the account

Fixed dollar risk is useful when you already know the amount you want to risk per trade. Percent of balance is closer to how many traders size personal accounts, because the risk changes as the balance changes.

For prop firm style accounts, percent of drawdown limit can be more realistic than percent of headline balance. A $50,000 account with a $2,500 drawdown limit does not give the same room as a personal account with $50,000 of real capital.

Example: a 55% win rate can still feel rough

Set win rate to 55%, reward/risk to 1R and simulate 100 trades. The system has a positive edge, but the outcome path can still include several losses in a row and a meaningful drawdown.

This is the main lesson: edge affects frequency over a larger sample. It does not control the order of wins and losses.

Use the equity curve to study the path, not just the result

The final number is only one part of the simulation. The equity curve shows the route taken to get there: early drawdowns, recovery periods, clustered losses and sudden runs of winners.

When you select outcomes in the history, the chart highlights that range so you can inspect how a specific sequence affected the sample. This makes it easier to separate a normal rough patch from a risk setting that is too aggressive.

Why losing streaks happen

A 60% win rate does not mean every ten trades will contain exactly six wins. Each trade is still uncertain. Over a small sample, several losses can appear in a row even when the long-term edge is positive.

That is why the maximum losing streak matters. It gives you a more realistic view of what a normal drawdown can feel like before you decide a system has stopped working.

Why sample size matters

The smaller the sample, the more the order of outcomes can distort your opinion. A good system can start with losses. A weak system can start with wins. Larger samples reduce that distortion, although they never remove uncertainty completely.

How the simulator calculates the main results

Observed win rate is wins divided by total trades. It can be very different from the configured win rate over a small sample.

Expectancy uses the observed sample: win rate times average winner, minus loss rate times average loser. Without dollar risk, it is shown in R. With dollar risk, it is shown in money.

Max losing streak is the longest sequence of losses in the simulated history. Max drawdown is the largest decline from a previous equity peak.

How to use the results without overreacting

Focus on the relationship between expected edge and observed path. If your simulated system has positive expectancy but still shows drawdowns, the lesson is not that drawdown is avoidable. The lesson is that risk must be small enough to survive normal variance.

Personal accounts and prop firm accounts answer different questions

A personal account simulation is mainly about balance path, drawdown tolerance and withdrawals. A prop firm style simulation is about rule survival: drawdown limit, trailing drawdown, thresholds and whether a payout can reduce the remaining cushion.

Run both models if you trade both environments. The same win rate and reward/risk can feel acceptable in a personal account and too aggressive inside a funded account rule set.

Frequently asked questions

Is this simulator predicting real market results?

No. It models random sequences based on the inputs you choose. It is educational, not a forecast.

Can I use this simulator as trading advice?

No. The simulator is a probability education tool. It does not recommend trades, position sizes, brokers, prop firms or account decisions.

Why does the observed win rate differ from the selected win rate?

Short samples are noisy. A configured 55% win rate does not mean every 100-trade sample must finish at exactly 55 wins.

Should I use personal account or prop firm style account?

Use personal account when you only want to model balance and manual withdrawals. Use prop firm style account when drawdown limits, trailing drawdown and withdrawal thresholds matter.

Why does the simulation stop?

With an account model active, the simulator stops if the next full-risk loss would exceed the account balance or the configured drawdown limit.

What does the equity curve show?

The equity curve shows the path of the simulated sample. It helps you inspect drawdowns, recovery periods, clustered losses and selected ranges from the outcome history.

Which risk mode should I use?

Use fixed dollar risk when you want a constant amount, percent of balance for account-based compounding, and percent of drawdown limit when a prop firm drawdown rule is the real constraint.