What your edge actually projects — with the variance
Every “how much can I make” calculator multiplies your expectancy by your trade count and prints one number. That number almost never happens. This one runs the months five thousand times and shows you the spread — the median, the bad month, the drawdown, the losing streak.
There is no single number — that is the whole point. Your expectancy sets the long-run average, but what you actually earn is a distribution, not a line. A trader with a genuine +0.3R edge taking 40 trades a month might have a median month of about +12R and still lose money in roughly one month in five, with a bad year drawing down 30R or more before it recovers. Enter your own win rate and average win and loss above and the tool shows your ranges — the median, the P10 month you have to survive, and your odds of a losing month — instead of one fantasy figure. Anyone quoting a single "day traders make $X" number is selling the average and hiding the variance that determines whether you survive to collect it.
Expectancy is the average result of a single trade over many trades, given your win rate and your average win and loss: (win rate × average winner) − (loss rate × average loser), usually measured in R, where 1R is your average loss. Positive expectancy means the strategy pays over time; negative means no amount of trade frequency or position sizing can save it. It says nothing about any one trade, or even any one month — a positive edge still hands you losing streaks and drawdowns along the way, which is exactly what this calculator makes visible instead of hiding behind the average.
Not on its own. Win rate is only half the equation. A 60% win rate with winners smaller than your losers can still lose money, and a 40% win rate with winners twice the size of your losers can be highly profitable. What decides it is expectancy, which combines win rate with the size of the wins and losses. A 60% win rate is "good" only when your average winner is at least comparable to your average loser — below that, the arithmetic turns against you no matter how often you are right. Put 60% into the calculator with your real average win and loss and see exactly where it lands.