Understanding your Sharpe ratio
There is no official regulatory threshold for a good Sharpe ratio, but the rule-of-thumb ranges below are widely used in investment practice when comparing portfolios measured over the same period.
| Sharpe ratio | Common interpretation |
|---|---|
| ≥ 1.0 | Commonly described as good — at least one unit of excess return per unit of volatility |
| 0.5 – 1.0 | Adequate — positive risk-adjusted return, but less excess return per unit of risk |
| < 0.5 | Poor — little or no excess return relative to the volatility taken (negative if the portfolio underperformed the risk-free rate) |
- The good/adequate/poor thresholds are practitioner rules of thumb, not regulatory or academic standards; appropriate benchmarks vary by asset class, strategy, and market regime.
- The Sharpe ratio uses standard deviation, which penalizes upside volatility the same as downside volatility and assumes returns are approximately normally distributed — it can overstate the quality of strategies with smooth returns but rare large losses.
- Sharpe ratios are only comparable when calculated over the same time period and frequency; annualized and monthly Sharpe ratios are not directly comparable, and past ratios do not predict future performance.
What is the Sharpe ratio?
The Sharpe ratio is a measure of risk-adjusted return that compares an investment's excess return — its return above a risk-free benchmark such as Treasury bills — to the volatility of its returns, measured by standard deviation. It answers the question of how much reward an investor received for each unit of risk taken, allowing portfolios with different risk levels to be compared on a common scale.
William F. Sharpe introduced the measure in a 1966 paper in the Journal of Business, originally calling it the reward-to-variability ratio; the finance profession later adopted the name Sharpe ratio. Sharpe was subsequently awarded the Nobel Memorial Prize in Economic Sciences in 1990 for his work on the theory of financial asset pricing.
Because the Sharpe ratio uses total volatility (standard deviation) as its risk measure, it treats upside and downside movements identically. It is best suited to comparing broadly diversified portfolios; related measures such as the Sortino ratio (downside deviation) and the Treynor ratio (beta) modify the risk denominator for other use cases.
How to use this Sharpe ratio calculator
- Enter the portfolio's annual return as a percentage — the actual or expected return of the investment being evaluated.
- Enter the risk-free rate for the same period, commonly proxied by the yield on short-term U.S. Treasury securities.
- Enter the standard deviation of the portfolio's returns as a percentage — the measure of how much returns fluctuate around their average.
- Read the Sharpe ratio and the excess return; higher ratios indicate more excess return earned per unit of volatility.
The formula behind the Sharpe ratio
The Sharpe ratio subtracts the risk-free rate from the portfolio return to isolate the excess return — the compensation for taking risk — and then divides that excess by the standard deviation of returns. The result is a dimensionless number: excess return earned per percentage point of volatility.
For example, a portfolio returning 8% when the risk-free rate is 3% has an excess return of 5 percentage points; with a standard deviation of 12%, the Sharpe ratio is (8 − 3) ÷ 12 ≈ 0.417. All three inputs must cover the same time period (typically annualized) for the ratio to be meaningful.
Common mistakes
- Comparing Sharpe ratios calculated over different time periods or frequencies — a monthly Sharpe ratio is not comparable to an annualized one without conversion.
- Treating the ratio as a forecast; it summarizes historical (or assumed) risk and return and does not predict future performance.
- Applying it to strategies with highly skewed or fat-tailed return distributions, such as option-selling strategies, where standard deviation understates the true downside risk.
- Using mismatched inputs, such as a nominal portfolio return with a risk-free rate from a different period or currency, which distorts the excess-return numerator.
- Comparing Sharpe ratios across very different asset classes or strategies as if a single threshold applied universally — context and peer-group comparison matter.
Pertanyaan yang sering diajukan
What is a good Sharpe ratio?
In common investment practice, a Sharpe ratio of 1.0 or higher is often described as good, between 0.5 and 1.0 as adequate, and below 0.5 as poor. These are practitioner rules of thumb rather than official standards, and sensible benchmarks vary by asset class, strategy, and the market environment over the measurement period.
Who invented the Sharpe ratio?
William F. Sharpe introduced the measure in a 1966 paper, "Mutual Fund Performance," published in the Journal of Business, where he called it the reward-to-variability ratio. Sharpe later received the 1990 Nobel Memorial Prize in Economic Sciences for his contributions to the theory of financial asset pricing.
Can the Sharpe ratio be negative?
Yes. A negative Sharpe ratio occurs whenever the portfolio's return is below the risk-free rate, meaning the investor took on volatility but earned less than a risk-free alternative. Ranking portfolios by negative Sharpe ratios is problematic, because among underperforming portfolios a higher standard deviation makes the ratio less negative without indicating better performance.
What risk-free rate should I use in the Sharpe ratio?
The risk-free rate should match the period and currency of the portfolio return being evaluated. For U.S. dollar portfolios, the yield on short-term U.S. Treasury bills is the most common proxy for annual calculations, since Treasury securities are conventionally treated as free of default risk.
What is the difference between the Sharpe ratio and the Sortino ratio?
The Sharpe ratio divides excess return by total standard deviation, penalizing upside and downside volatility equally, while the Sortino ratio divides excess return by downside deviation only, penalizing only returns below a target. The Sortino ratio is sometimes preferred for strategies with asymmetric return distributions, where upside volatility is not considered a drawback.
Referensi
- Sharpe WF. Mutual Fund Performance. Journal of Business, 1966;39(1):119–138.
- Sharpe WF. The Sharpe Ratio. Journal of Portfolio Management, 1994;21(1):49–58.
- CFA Institute. Portfolio Risk and Return — CFA Program Curriculum. cfainstitute.org.
- U.S. Securities and Exchange Commission, Investor.gov. Assessing risk and investment performance. investor.gov.