The Calmar ratio measures a strategy's return relative to its worst drawdown — specifically, annualized return divided by maximum drawdown. Where the Sharpe and Sortino ratios measure return against volatility, Calmar measures it against the single most painful peak-to-trough loss the strategy endured.
Why max drawdown is the right denominator
Volatility is an abstraction; a deep drawdown is what actually ends traders — it's what forces you to quit, blows past your risk tolerance, or triggers ruin. By dividing return by the worst drawdown, Calmar asks the most practical question: was the return worth the maximum pain you had to sit through to get it? A strategy returning 30% with a 15% max drawdown (Calmar 2.0) is more livable than one returning 40% with a 40% drawdown (Calmar 1.0).
What "good" looks like
Broadly, a Calmar above 1 means annual return exceeds the worst drawdown; above 2-3 is strong. Like all such ratios, the absolute number depends on timeframe and market, so it's best used to compare your own strategies on equal footing, which one delivered more return per unit of maximum agony.
Volatility is a statistic. Max drawdown is the number that decides whether you're still trading next year.
Using it
Calmar is the metric that respects survivability — it directly rewards keeping drawdowns shallow, which is the same discipline behind conservative position sizing. Pair it with Sharpe, Sortino, profit factor, and expected value for a full picture. No single number captures a strategy, but Calmar keeps the focus where it belongs: on the drawdown that could take you out of the game.