Metrics That Actually Matter
Net profit is the least informative number on a backtest report.
Net profit is the first number everyone looks at and the least informative one on the report. It tells you nothing about how much risk was taken to get it, or whether the result could have happened by chance.
A handful of other metrics tell you far more, and reading them together is what separates a serious evaluation from a screenshot.
Edge: expectancy and profit factor
Expectancy is the average currency amount made per trade. Profit factor is gross profit divided by gross loss. Both describe the same underlying thing from different angles, and both should be calculated net of costs.
A profit factor above 1.0 is profitable, but 1.2 is fragile once costs and slippage move slightly. Anything above 2.0 on a decent sample deserves scepticism before celebration — it is often a sign of a short sample or an unlucky-free period.
Pain: drawdown and its duration
Maximum drawdown is the largest peak-to-trough decline in equity. Its duration is how long the strategy spent underwater. Both matter, and duration is the more emotionally loaded of the two.
Combine them with return to get a sense of whether the strategy is tradeable by a human being. A strategy returning 40% a year with a fourteen-month drawdown is technically excellent and practically untradeable for most people.
Risk-adjusted return
The Sharpe ratio divides excess return by the standard deviation of returns. It rewards consistency and penalises volatility. Sortino refines this by penalising only downside deviation, which most traders find more meaningful.
These are comparative tools, not absolute targets. Use them to compare strategies or parameter sets against each other, not to decide whether something is good in isolation.
VaR Calculator
Calculate Value at Risk to understand potential portfolio drawdowns in extreme scenarios.
Sample size is the gate
Every metric above is meaningless below a certain number of trades. Thirty trades is anecdote. Two hundred is a beginning. Below that threshold, your metrics are dominated by variance and will not reproduce.
This is the single most common reason a trader's live results diverge from their test. The test looked excellent because it contained forty trades, one of which was enormous. Nothing was wrong except the sample.
What to look at on a backtest report, and in what order
| Metric | What it tells you | Warning sign |
|---|---|---|
| Trade count | Whether anything else is meaningful | Under 100 trades |
| Expectancy | Average profit per trade after costs | Negative or near zero |
| Profit factor | Gross profit relative to gross loss | Below 1.3 |
| Max drawdown | The pain you must sit through | Larger than you can tolerate |
| Drawdown duration | How long you sit through it | Months longer than your patience |
| Sharpe / Sortino | Return per unit of risk | Compared across strategies only |
Key takeaways
- Net profit without a risk measure tells you almost nothing
- Expectancy and profit factor describe the edge; drawdown describes the cost of holding it
- Sharpe and Sortino are for comparing strategies, not for absolute judgement
- Below roughly 100 trades, no metric on the report is statistically meaningful
- Profit factor and expectancy describe the edge
- Maximum drawdown and its duration describe the pain
- Sharpe and Sortino adjust return for the risk taken
- Trade count determines whether any of it is statistically meaningful
Celebrating an excellent profit factor built on fewer than thirty trades.
Reading is not verification
Take the concept you just read and turn it into explicit rules, then test it. That is the only way to know whether it actually works.
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