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.