Calculator
Expectancy Calculator
Expectancy Calculator
Expectancy per Trade
$95.00
Win/Loss Ratio
1.78x
Breakeven Win Rate
36.0%
Edge Analysis
A positive win-rate system with a 1.78x win/loss ratio produces an expectancy of $95.00 per trade (1.90% of the $5,000 at risk). That is a genuine long-run edge — the breakeven win rate is only 36%, so there is a meaningful margin of safety before the edge disappears.
Expectancy is an estimate based on the win rate, win size, and loss size you enter. Actual results vary from trade to trade. This is a math tool, not a prediction or a recommendation to trade.
Expectancy: The True Measure of a Trading System's Edge
Most traders obsess over win rate, but win rate alone tells you almost nothing about whether a strategy makes money. A strategy that wins 80% of the time can still lose if its wins are tiny and its losses are large, while one that wins only 35% of the time can be highly profitable if each win is several times each loss. The statistic that combines both dimensions is expectancy — the average amount you expect to make or lose per trade over many repetitions. Expectancy is found by weighting the average win by the probability of winning and the average loss by the probability of losing, and it is the number that reveals whether a system has a genuine edge. For US traders and active investors, expectancy reframes every decision. It converts a vague feeling about a strategy into a concrete per-trade number that can be multiplied across a planned number of trades, turning a question of instinct into a question of arithmetic. It also exposes the most dangerous trap in trading: the emotionally satisfying high win rate that is quietly unprofitable, and the uncomfortable losing-streak-heavy strategy that is quietly rich. By making the edge visible before capital is at risk, expectancy is the single most important calculation for anyone who takes more than a handful of trades on any system.
Behind the Formula: Win Rate Weighted by Payoff
Expectancy per trade is computed as (Win Rate x Average Win) − (Loss Rate x Average Loss). Each outcome is weighted by how often it occurs, so a rare large win still pulls the expectancy up, and a rare catastrophic loss pulls it down. The result is the arithmetic expected value of one trade — the amount you would average if you could run the setup an infinite number of times. Because it is an expectation, any single trade or even a short string of trades can land far from it, but over many repetitions the average result gravitates toward the expectancy. The calculator then multiplies the expectancy by the number of trades to project the expected net over a planned run, and it computes the breakeven win rate — the win fraction at which expected wins exactly equal expected losses. The breakeven win rate is the survival line for the strategy: if your realistic accuracy sits above it, you have a positive edge; below it, the system is a losing machine no matter how good it feels. It also reports the win/loss ratio (average win divided by average loss), which together with the win rate fully characterizes the strategy's profit structure. A positive expectancy with a comfortable margin over breakeven is the definition of a durable edge.
Expert Insights
Expectancy Beats Win Rate, Every Time
The single most common mistake in trading is optimizing win rate instead of expectancy. A strategy that wins 90% of the time at +$20 per win but loses $200 when it loses has a deeply negative expectancy. Conversely, a trend system winning 40% of the time at 3:1 payoffs is strongly positive. Judge every system by its expectancy, not by how often it feels like a winner — frequency of reward is an emotional property, expectancy is a financial one.
Your Edge Shrinks After Costs — Measure the Real Number
The calculator's expectancy is gross of commissions, spread, and slippage. Every round trip subtracts a fixed cost, and for short-horizon high-frequency trading that cost can exceed the gross edge entirely. Always subtract your realistic per-trade cost from the expectancy before concluding you have anything. A gross edge of $20 per trade that costs $25 in friction to capture is a losing system wearing an edge's costume.
Variance Can Hide Your Edge for a Long Time
Even a strongly positive-expectancy system will deliver long losing streaks by pure chance, and many traders abandon a good strategy during one of them. The margin between your win rate and the breakeven win rate is your cushion against that variance — the wider it is, the longer a bad run can persist before your confidence should actually be in question. Track expectancy over enough trades to let the average stabilize before judging whether the system has broken down or is just experiencing normal randomness.
Actionable Tips
- 1
Validate a System With Expectancy Before Going Live
Before trading real money, run a backtest or paper test over a meaningful number of trades, compute the average win, average loss, and win rate, and plug them here. Only strategies whose expectancy is positive, survives cost deductions, and clears the breakeven win rate by a margin deserve live capital. This single screen rejects the majority of appealing-but-unprofitable ideas.
- 2
Track Your Real Numbers, Not Your Story
Keep a journal that records the outcome of every trade, then periodically recompute your average win, average loss, and win rate. Compare the resulting expectancy to earlier readings. Drift in expectancy is the earliest honest signal that your edge is fading, and it beats gut feeling for detecting the moment a once-good system needs adjustment or retirement.
- 3
Size Positions From Expectancy and Risk Tolerance
Once you know the expectancy per unit of risk, position size should scale with account risk tolerance, not with confidence in any single trade. Risk a fixed small fraction of the account per trade so the system's positive expectancy plays out across many repetitions. Overconfidence sizing on individual trades is how traders ruin themselves even with an edge.
Real-World Examples
Dana's High-Win-Rate System Was Quietly Losing
Dana was proud of winning 78% of her options trades. But the calculator revealed her wins averaged $90 while her losses averaged $420, producing a negative expectancy of -$43 per trade. The frequent small wins felt great while bleeding her account. She widened her profit targets and tightened stops, flipping the expectancy positive without needing to change her win rate.
Victor Learns to Trust a Losing-Streak System
Victor's trend-following approach won only 42% of the time, and he kept second-guessing it during the inevitable losing runs. The tool showed his large winners produced an expectancy of +$71 per trade, with a breakeven win rate of just 30%. Knowing he had a 12-point cushion, he held through the losing streaks with confidence and let the positive expectancy compound over hundreds of trades.
The Park Family Prices a Swing-Trading Plan
Before committing capital to a swing strategy, the Parks modeled it at 52% wins, $260 average gains, and $170 average losses. Expectancy came to +$39 per trade gross, which shrank to a marginal +$9 after commission and slippage. They concluded the edge was too thin for their costs and chose a wider-stopped, lower-frequency approach that preserved its expectancy after friction.
Glossary of Terms
- Expectancy
- The average profit or loss expected per trade, computed as win rate times average win minus loss rate times average loss. Positive expectancy is a genuine edge.
- Win/Loss Ratio
- Average win divided by average loss. It measures payoff size independent of how often wins occur.
- Breakeven Win Rate
- The win percentage at which expected wins exactly equal expected losses. A real win rate above it means a positive edge.
Frequently Asked Questions
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Ivy Sinclair-Wren
Financial Chaos Analyst
Ivy Sinclair-Wren is a Financial Chaos Analyst covering investing, AI, wealth psychology, and the emotional consequences of opening finance apps during market crashes. Based in Melbourne, she specializes in demystifying the US tax code and helping users navigate the intersection of spreadsheet logic and human irrationality.