Two investments deliver 10% per year over a decade. One barely budged along the way; the other had a 50% drawdown midway. Should you treat them as equal? The Sharpe ratio says no.
The Formula
Sharpe ratio = (Portfolio return − Risk-free rate) / Standard deviation of returns
In plain English: how much extra return did you get for each unit of volatility you absorbed? Higher is better.
A Real Example
- Fund A: 10% return, 6% volatility, 4% risk-free → Sharpe ≈ 1.00
- Fund B: 10% return, 18% volatility, 4% risk-free → Sharpe ≈ 0.33
Both delivered 10%, but Fund A did it three times more efficiently. Over decades, the smoother fund is also less likely to push you into selling at the bottom.
Why It Matters in Practice
The Sharpe ratio gives a number to a feeling. The wild-ride fund might look exciting on its best year, but a low Sharpe ratio means most of the return came from luck of timing — not durable skill.
Limits of Sharpe
- Treats upside and downside volatility identically (the Sortino ratio fixes this).
- Assumes returns are roughly normally distributed (they aren't, especially in crises).
- Past Sharpe doesn't always predict future Sharpe.
How to Use It
When choosing between funds in the same category, prefer the higher Sharpe ratio. Most fund websites and Morningstar pages publish it. Our ROI Calculator and CAGR Calculator give you the return inputs; subtract a 4% risk-free rate and divide by the fund's standard deviation to compute your own.
Bottom Line
Total return tells you what an investment earned. Risk-adjusted return tells you whether it was worth it. Both matter.
Run the numbers yourself
Plug your own inputs into our free calculators — no signup.