Sharpe Ratio Calculator

What is the Sharpe ratio?

The Sharpe ratio measures the return of an investment per unit of risk, where risk is defined as the standard deviation of returns. Developed by William Sharpe in 1966, it is the most widely used risk-adjusted performance metric in portfolio management. A higher Sharpe ratio indicates that an investment generated more return per unit of volatility — meaning better risk-adjusted performance, not just better raw returns.

The Sharpe ratio is most meaningful when comparing two portfolios or strategies with similar objectives. A portfolio with a 15% annual return and a 20% standard deviation (Sharpe = 0.5) is generating less risk-adjusted return than a portfolio with a 10% return and a 7% standard deviation (Sharpe = 0.71). Raw return alone doesn't tell you this — Sharpe does.

The Sharpe ratio formula

The Sharpe ratio uses the risk-free rate as the baseline return that requires no risk to achieve:

Sharpe Ratio = (Portfolio Return − Risk-Free Rate) / Standard Deviation of Returns

Portfolio Return — the annualized total return of the portfolio. Risk-Free Rate — the return available on a riskless asset; the 3-month US Treasury bill is the most common proxy (approximately 5.1–5.3% as of mid-2025, down from the 2023 peak of ~5.5%). Standard Deviation — the annualized standard deviation of portfolio returns, measuring the volatility of the return stream.

Worked example

A US equity portfolio delivered a 13.2% annual return over the past 3 years with an annualized standard deviation of returns of 16.4%. The current 3-month T-bill rate is 5.1%.

• Step 1: Excess return = 13.2% − 5.1% = 8.1%.
• Step 2: Standard deviation = 16.4%.
• Step 3: Sharpe ratio = 8.1% / 16.4% = 0.494.

Compare to a bond-heavy portfolio: 7.0% return, 5.8% standard deviation. Sharpe = (7.0 − 5.1) / 5.8 = 0.328. The equity portfolio earns a higher Sharpe ratio — it generated more excess return per unit of risk — even though the raw return difference was 6.2%. The bond portfolio appeared "safer" by volatility, but not efficient relative to the risk-free alternative.

When to use the Sharpe ratio calculator

Use the Sharpe ratio any time you want to compare investment performance on a risk-adjusted basis rather than just raw returns.

• Comparing mutual funds or ETFs: Two S&P 500 funds with different histories (different inception dates, different manager periods) may have different Sharpe ratios — reflecting differences in implementation, expense ratios, and tracking error. Sharpe normalizes these for comparison.
• Evaluating a trading strategy: A systematic trading strategy with a 20% annual return but a Sharpe of 0.4 is less attractive than a strategy with 12% return and a Sharpe of 1.2. High Sharpe strategies attract institutional capital because they can be leveraged without taking excessive absolute risk.
• Portfolio construction: When adding a new asset to a portfolio, the marginal Sharpe ratio — how much does this asset improve the portfolio's overall Sharpe — is a useful input. Assets with low correlation to the existing portfolio can improve Sharpe even if their own individual Sharpe is modest.
• Hedge fund and factor allocation: Institutional allocators routinely require Sharpe ratios above 0.7–1.0 before allocating to a manager. Understanding where your personal portfolio sits on this scale helps contextualize your investment performance.

Common mistakes

The Sharpe ratio is frequently calculated or interpreted incorrectly.

• Using the wrong risk-free rate: The risk-free rate must match the measurement period and currency. For a US dollar portfolio measured over 2025, the 3-month T-bill yield (~5.1%) is appropriate — not a 10-year Treasury yield, and not a 2020 rate of 0.1%. Using an outdated risk-free rate can dramatically distort the Sharpe ratio.
• Calculating Sharpe on too short a period: Sharpe ratios based on fewer than 24–36 months of data are highly sensitive to the specific period measured and to outlier return months. A 3-month period during a bull market will produce an inflated Sharpe that is not representative of long-run performance.
• Treating Sharpe as the only risk metric: Sharpe uses standard deviation — which penalizes both upside and downside volatility equally. A strategy with occasional large positive outliers (asymmetric upside) will appear worse on Sharpe than Sortino ratio, which only penalizes downside volatility. Conversely, strategies with frequent small gains and rare large losses (negative skewness) can look excellent on Sharpe while hiding catastrophic tail risk.
• Comparing Sharpe ratios across different frequencies: Monthly Sharpe ratios cannot be directly compared to annual ones without proper annualization. To annualize a monthly Sharpe: multiply by √12. To annualize a daily Sharpe: multiply by √252 (trading days per year).

Limitations of the Sharpe ratio

The Sharpe ratio assumes that returns are normally distributed — that large gains and losses are equally likely and that returns follow a bell curve. In practice, financial returns exhibit fat tails (kurtosis) and negative skewness — large negative returns occur more frequently than a normal distribution predicts. A strategy that looks good on Sharpe can have significant unmodeled tail risk. For this reason, the Sortino ratio (which uses downside deviation instead of total standard deviation) or the Calmar ratio (return / maximum drawdown) are often more informative for strategies with asymmetric return profiles.

Sharpe also does not account for liquidity risk. A private equity or real estate portfolio may show excellent Sharpe metrics simply because it is not marked to market daily — the apparent smoothness of returns reflects infrequent pricing, not low true volatility. This is sometimes called "Sharpe inflation" from stale pricing, and it is why institutional allocators apply liquidity adjustments before comparing illiquid and liquid asset Sharpe ratios.

Frequently asked questions

What is a good Sharpe ratio?

As a rough benchmark: a Sharpe ratio below 1.0 is considered suboptimal for a dedicated investment strategy (though broad equity indices often produce 0.4–0.6 over long periods); 1.0–2.0 is considered good; above 2.0 is excellent and typically associated with systematic strategies, long-short hedge funds, or factor-based models. The S&P 500's long-run Sharpe ratio is approximately 0.4–0.6, depending on the period measured and the risk-free rate used.

What is the difference between Sharpe and Sortino ratio?

The Sortino ratio replaces the standard deviation in the Sharpe denominator with downside deviation — the standard deviation of returns below a minimum acceptable return (usually 0% or the risk-free rate). This penalizes only downside volatility, not upside. For strategies with asymmetric returns (options selling, trend following), the Sortino ratio is typically a more accurate measure of the quality of risk-taking than Sharpe.

What risk-free rate should I use in 2025?

For US dollar-denominated portfolios in 2025, the 3-month US Treasury bill yield is the standard risk-free rate proxy — approximately 5.1–5.3% as of mid-2025. You can find the current yield at TreasuryDirect.gov or on the Federal Reserve H.15 release. For periods before 2022, when rates were near zero, the risk-free rate was commonly set to 0% or the 10-year Treasury yield for longer-duration analysis.

Can a portfolio have a negative Sharpe ratio?

Yes. A negative Sharpe ratio means the portfolio's return was below the risk-free rate — meaning you were better off holding Treasury bills than taking the risk you took. A negative Sharpe is most informative when the portfolio also had significant volatility, confirming poor risk-adjusted performance. If both the excess return and volatility are very small, the Sharpe ratio's sign is less meaningful.

Related calculators

The Sharpe ratio is most useful in context with these performance tools:

• CAGR Calculator — calculate the annualized return that forms the numerator of the Sharpe ratio for any portfolio period.