Sharpe Ratio Calculator

What This Calculator Does

Two funds both returned 12% last year. One had a smooth ride with minimal ups and downs. The other swung wildly, losing 15% in a single month before recovering. Which is the better investment? The Sharpe ratio answers this by measuring return per unit of risk. A higher Sharpe ratio means you got more reward for the volatility you endured.

The Sharpe Ratio Calculator measures risk-adjusted returns. It takes the excess return of a portfolio above the risk-free rate and divides it by the standard deviation of those returns. The result is a single number that lets you compare investments with different return and volatility profiles on equal footing. The calculator supports two modes: entering summary statistics (return, risk-free rate, standard deviation) or pasting a series of period returns from which the mean and standard deviation are computed automatically.

The Sharpe ratio was developed by Nobel laureate William F. Sharpe and is the most widely used measure of risk-adjusted performance in professional finance. According to Investopedia, a Sharpe ratio above 1.0 is considered acceptable, above 2.0 is considered excellent, and above 3.0 is exceptional. The ratio is used by pension funds, endowments, and retail investors to evaluate fund managers and compare asset allocation strategies.

Inputs Required

In Summary mode:

• Portfolio Annual Return: The average yearly return of the portfolio
• Risk-Free Rate: The return on a risk-free asset, typically the 10-year Treasury yield
• Standard Deviation: The annual volatility of the portfolio returns

In Period Returns mode:

• Monthly Returns: A list of monthly return percentages, separated by commas
• Risk-Free Rate: The annual risk-free rate (the calculator handles the conversion)

Outputs Provided

• Sharpe Ratio: The risk-adjusted return measure
• Excess Return: Portfolio return minus the risk-free rate
• Annualized Sharpe: In Period Returns mode, the monthly Sharpe annualized by multiplying by the square root of 12
• Mean and Standard Deviation: Computed from the entered returns in Period Returns mode
• Assessment: A contextual reading of the Sharpe ratio value
• Returns Chart: A bar chart of the entered period returns in Period Returns mode

How the Calculation Works

The Sharpe ratio divides the excess return by the standard deviation of returns. Excess return is the portfolio return minus the risk-free rate. Standard deviation measures how much the returns vary around the average.

The numerator (excess return) is the compensation you receive for taking risk above what a risk-free investment would pay. The denominator (standard deviation) is the amount of risk you took. The ratio tells you how much excess return you earned per unit of volatility. A portfolio returning 10% with a 15% standard deviation and a 4.5% risk-free rate has a Sharpe ratio of (10 - 4.5) / 15 = 0.367. That is a modest result: the excess return does not fully compensate for the volatility.

When using monthly returns, the calculator computes the monthly Sharpe ratio and then annualizes it by multiplying by the square root of 12 (approximately 3.464). This is the standard method because returns scale with the square root of time while standard deviation does the same, so the ratio annualizes cleanly.

How to Use the Calculator

1. Choose your mode. Use Summary Stats if you know the annual return and standard deviation. Use Period Returns if you have a list of monthly returns.
2. In Summary mode, enter the portfolio annual return, standard deviation, and risk-free rate.
3. In Period Returns mode, paste your monthly returns separated by commas. Enter the annual risk-free rate.
4. Read the Sharpe ratio. Check the assessment for context on what the number means.

For the risk-free rate, the 10-year Treasury yield is the most common choice. As of September 2026, it is approximately 4.77%. Some practitioners use the 3-month T-bill yield (about 3.89% in September 2026) for a shorter-term benchmark. Use whichever matches your investment horizon. For comparing average returns and volatility without the risk-free adjustment, use our Average Return Calculator.

Example Calculations

Example 1: An S&P 500 Index Fund

An S&P 500 index fund has a long-term annual return of about 10% with a standard deviation of 16%. Using a 4.5% risk-free rate, the Sharpe ratio is (10 - 4.5) / 16 = 0.344. This is a typical Sharpe ratio for broad U.S. equities. It tells you that for every unit of volatility, you earned 0.344 units of excess return above the risk-free rate. Historically, the S&P 500 has had a long-term Sharpe ratio around 0.3 to 0.5, which is considered acceptable but not exceptional.

Example 2: A Hedge Fund Strategy

A market-neutral hedge fund returns 9% annually with a standard deviation of only 5%. Using the same 4.5% risk-free rate, the Sharpe ratio is (9 - 4.5) / 5 = 0.90. The fund returns less than the S&P 500 in absolute terms, but its Sharpe ratio is nearly three times higher because it takes far less risk. This is the core insight of risk-adjusted returns: a lower-returning, lower-volatility strategy can be superior on a risk-adjusted basis. This is why institutional investors use the Sharpe ratio rather than raw returns to evaluate managers.

Real World Scenarios

Comparing Two Portfolio Allocations

Portfolio A is 100% stocks, returning 11% with 18% volatility. Portfolio B is 60% stocks and 40% bonds, returning 8.5% with 11% volatility. At a 4.5% risk-free rate, Portfolio A has a Sharpe of (11 - 4.5) / 18 = 0.361. Portfolio B has a Sharpe of (8.5 - 4.5) / 11 = 0.364. The diversified portfolio has a slightly better risk-adjusted return despite lower absolute returns. Adding bonds reduced volatility more than it reduced return, improving the ratio. This is the theoretical basis for diversification.

Evaluating a High-Return, High-Volatility Fund

A tech-focused fund returned 25% last year with a standard deviation of 35%. The risk-free rate is 4.5%. The Sharpe ratio is (25 - 4.5) / 35 = 0.586. The absolute return is impressive, but the risk-adjusted return is modest because the volatility is so high. An investor who cannot tolerate a 35% swing in portfolio value may not be able to hold the fund through a downturn, which means the high return may not be achievable in practice. The Sharpe ratio reveals this tradeoff.

A Negative Sharpe Ratio

A commodity fund returned 3% while the risk-free rate was 4.5% and the standard deviation was 22%. The Sharpe ratio is (3 - 4.5) / 22 = -0.068. The negative ratio means the fund returned less than a risk-free Treasury while taking on significant volatility. The investor would have been better off in a government bond with zero volatility. A negative Sharpe ratio is a clear signal that the investment did not compensate for its risk.

Common Mistakes to Avoid

• Comparing Sharpe ratios across different time periods: A Sharpe ratio calculated over a bull market will look better than one calculated over a bear market, even for the same fund. Always compare ratios computed over the same time horizon and frequency.
• Using the wrong risk-free rate: The risk-free rate should match your investment horizon. For long-term equity analysis, the 10-year Treasury yield is standard. For short-term strategies, the 3-month T-bill is more appropriate. Using a stale or mismatched rate distorts the ratio. As of September 2026, the 10-year Treasury yields about 4.77% and the 3-month T-bill yields about 3.89%.
• Assuming normal distribution of returns: The Sharpe ratio uses standard deviation, which assumes returns are normally distributed (bell-shaped). Real market returns have fat tails: extreme events happen more often than a normal distribution predicts. The Sharpe ratio understates the risk of strategies with negative skew or fat tails, such as option-selling strategies.
• Ignoring the Sortino ratio for downside risk: The Sharpe ratio penalizes all volatility, including upside volatility. The Sortino ratio penalizes only downside deviation, which is what investors actually fear. For strategies with positively skewed returns, the Sortino ratio may be a better measure. The Sharpe ratio remains the industry standard, but it is not the only tool.

Limitations of This Calculator

This tool calculates the Sharpe ratio from the inputs you provide. In Summary mode, it assumes the return and standard deviation are annual figures. In Period Returns mode, it assumes monthly returns and annualizes by multiplying by the square root of 12. It does not account for skewness, kurtosis, or fat tails in the return distribution. It uses standard deviation as the risk measure, which treats upside and downside volatility equally. The risk-free rate is a single constant value and does not vary over the period. For a more complete risk analysis, consider the Sortino ratio, maximum drawdown, and Value at Risk alongside the Sharpe ratio. For comparing arithmetic and geometric returns, use our Average Return Calculator.

Authoritative Research and Resources

• Investopedia: Sharpe Ratio - A detailed explanation of the Sharpe ratio formula, interpretation, and limitations, including how to use it for portfolio comparison.
• U.S. Treasury: Daily Treasury Yield Curve Rates - Official daily Treasury yields for all maturities, which you can use as the risk-free rate input. The 10-year yield is the most common choice for long-term investment analysis.

For related tools, try our Average Return Calculator to compare arithmetic and geometric means, our CAGR Calculator for annualized returns, or our ROI Calculator for total return on investment.