Sharpe Ratio Calculator

What the Sharpe Ratio Measures

The Sharpe ratio answers a simple but powerful question: for every unit of volatility you accepted, how much excess return did you earn? It strips out the "free lunch" of the risk-free rate — today roughly the 3-month T-bill yield around 4% — and divides what's left by the standard deviation of your returns. The formula is: Sharpe = (Return − Risk-Free Rate) / Standard Deviation. A Sharpe of 1.0 means you earned 1% of excess return for each 1% of annualized volatility — a reasonable trade.

The ratio was developed by Nobel laureate William Sharpe in 1966 as a way to compare investments on a level playing field. Two portfolios might both return 12% — but if one did it with 8% volatility and the other with 20% volatility, they are not equivalent choices. The Sharpe ratio makes the comparison explicit: the first portfolio earned far more per unit of risk accepted.

One key limitation: the Sharpe ratio uses standard deviation as its measure of risk, which treats upside and downside volatility identically. A stock with a few large gains will be "penalized" as risky. Investors who care only about downside risk use the Sortino ratio instead, which divides by downside deviation only. For most purposes, the Sharpe ratio remains the standard benchmark.

How to Interpret Your Sharpe Ratio

Context matters enormously. A Sharpe of 0.5 is mediocre for a concentrated stock pick but typical for a broad market index fund. The S&P 500 has averaged around 0.5 over most long measurement windows — meaning most active managers who beat this benchmark on a risk-adjusted basis are doing genuinely well. A ratio above 1.0 is considered good; above 2.0 is exceptional and relatively rare outside strategies with survivorship bias.

A negative Sharpe ratio means the investment returned less than a risk-free T-bill. You took on price volatility and were not compensated for it. This can happen in bear markets or with underperforming individual stocks — it does not necessarily mean the investment lost money in absolute terms, just that it underperformed the risk-free rate on a risk-adjusted basis.

Compare Sharpe ratios only within the same asset class and strategy. A hedge fund's 1.5 Sharpe uses leverage, derivatives, and active timing — it is not directly comparable to an index fund's 0.5. Also compare over the same time period: Sharpe ratios calculated over different windows or in different market regimes (bull vs. bear) are not apples-to-apples.