Sharpe Ratio Calculator

The Sharpe ratio asks whether a return compensated for the volatility taken to earn it. It is excess return per unit of volatility: the portfolio return less a low-risk baseline, divided by the standard deviation of the portfolio's returns. A ratio of 1.0 means each point of volatility came with one point of excess return. Two portfolios with the same return and different ratios differ in how much volatility they carried to get there.

The formula in plain terms

Sharpe is the portfolio return less the baseline rate, divided by the portfolio's standard deviation. All three figures must be on the same period basis: an annual return against a monthly standard deviation produces a number roughly three and a half times too large, and nothing in the arithmetic can detect the mismatch. The numerator is the excess return over the baseline; the denominator is the volatility that came with it.

What the bands mean

These bands are conventional reference points rather than thresholds with a formal basis. Below 0 the portfolio returned less than the baseline. From 0 up to 0.5 sits the lower end of the commonly quoted range, 0.5 up to 1.0 the middle, 1.0 up to 2.0 the upper end. Ratios from 2.0 up to 3.0 are uncommon over long periods, and figures of 3.0 and above are rarer still and usually attach to short windows or narrow strategies. Each band includes its lower bound and excludes its upper one, so a ratio of exactly 1.00 falls in the 1.0 up to 2.0 band. The panel reports which band the computed figure falls in.

Long-run figures for broad developed-market equity indices are commonly quoted in the region of 0.4 to 0.6, though the number moves with the period measured and the baseline rate chosen.

Which inputs move the result most

Measured per percentage point, both the return and the baseline move the ratio by one divided by the standard deviation, equal in size and opposite in sign. Volatility, again per percentage point, moves it by the ratio divided by the standard deviation, which is another way of saying that a point of volatility costs a fixed fraction of the ratio itself. On that per-point basis, which lever is stronger depends on where the ratio sits: below 1.0 the return and baseline dominate, above 1.0 volatility does, and at exactly 1.0 the two are equal. On a proportional basis, where each input moves by 1% of its own value, the picture differs, because a percent of a 4% baseline is a far smaller move than a percent of a 12% return.

Return and risk answer different questions

Take two portfolios over ten years. Portfolio A returns 12% a year with a 25% standard deviation; portfolio B returns 9% with 12%. Raw return favours A. At a 4% baseline the ratios are 0.32 and about 0.42, so B produced more excess return per point of volatility. What that does not settle is which compounded higher: the geometric return is roughly the arithmetic return less half the variance, which puts A near 8.9% and B near 8.3%. The ratio and the compounded outcome answer different questions.

The baseline rate

The ratio depends on which baseline is used. A short-horizon analysis conventionally uses a three-month government bill yield, a long-horizon one a ten-year government bond yield, and a historical comparison the average yield across the period being measured. Using a current rate for a period when rates were far lower distorts the figure, and comparisons across periods need a baseline appropriate to each.

Diversification and the ratio

Combining assets that are not perfectly correlated produces a portfolio with lower volatility than the weighted average of its parts. Whether that raises the ratio depends on the trade: the ratio rises when the return given up per point of volatility removed is less than the current ratio, and falls when it is more. A shift that costs 1.5 points of return to remove 3 points of volatility gives up 0.5 per point, so it raises the ratio only where the ratio already exceeds 0.5. The same shift at a starting ratio of 0.31 lowers it.

What the ratio does not capture

The measure assumes returns are normally distributed. They generally are not: return distributions have fatter tails than a normal distribution implies, so the ratio understates the chance of extreme outcomes and flatters strategies that are stable most of the time and occasionally are not.

It treats upside and downside volatility identically. A portfolio with 20% upside volatility and none on the downside scores the same as one split 10% and 10%. The Sortino ratio substitutes downside deviation for total standard deviation to address that; the multiple between the two is not fixed and depends on the shape of the distribution.

The ratio is period-sensitive. Annualised figures vary substantially with the window chosen, and short windows are noisy.

Below zero the ratio stops ranking portfolios in a usable way. With a negative excess return, a larger standard deviation produces a smaller negative number: at a 2% return against a 4% baseline the ratio reads −0.40 at 5% volatility and −0.05 at 40%. The arithmetic is correct in each case, but a higher figure no longer means a better outcome, so comparisons across the zero line do not hold.

Funds that perform badly are more likely to close, so the ratios visible across a surviving fund universe are drawn from a filtered sample.

What this calculator shows

The tool computes the ratio from a portfolio return, a baseline rate and a standard deviation. It does not gather return history, derive standard deviation from monthly data, or compare against a benchmark. The panel reports the excess return, the band the figure falls in, the return that would produce a ratio of 1.00 at the volatility entered, and the ratio measured against a zero baseline. The excess return carries a second reading worth noting: because the ratio is excess divided by volatility, the excess figure is also the standard deviation at which the ratio would read exactly 1.00.