The Sharpe ratio punishes good volatility too. Enter your return, a target rate and your downside deviation to get the Sortino ratio — the measure that only counts the swings that actually hurt you.
Answer first: the Sortino ratio measures how much return you earned per unit of downside risk. This Sortino ratio calculator subtracts your target rate from your return and divides by your downside deviation — the volatility of only the losing periods — so a strategy is rewarded for upside surprises instead of penalized for them.
Sortino = (Return − Target rate) ÷ Downside deviation
Example: a portfolio returning 12% against a 4% target, with a downside deviation of 9%, has a Sortino of (12 − 4) ÷ 9 = 0.89. Compare that to its Sharpe ratio, which would use total volatility and usually look lower.
The Sortino ratio exists because the Sharpe ratio has a quirk: it treats every wobble as risk, including the big up-days you actually want. Frank Sortino's refinement only counts volatility below a target you set, isolating the moves that genuinely cause pain. For income strategies, hedge funds and anything with asymmetric returns, it's often the fairer scoreboard.
Downside deviation isn't on most brokerage screens — you compute it from a return series by taking only the periods that fell below your target, squaring those shortfalls, averaging and taking the square root. Many fund fact sheets and portfolio analytics tools report it directly. If you only have total standard deviation, use the Sharpe ratio instead; the two ratios answer slightly different questions and are best read together.
Reality check: The result is only as good as the downside-deviation figure you feed it, and like all such ratios it depends on the measurement period and assumes the past is a guide. It can still flatter strategies with rare, catastrophic tail risk. This is an educational calculator, not financial advice — verify your own numbers and see the U.S. SEC at investor.gov.
Pair it with the Sharpe ratio calculator, the beta calculator for market risk, understand what market volatility is, and review risk management basics.
Last updated 25 June 2026 · Written by Mustafa Bilgic. Educational only — not financial advice.
The Sortino ratio measures risk-adjusted return using only downside volatility. It divides the return above a target (often the risk-free rate) by the downside deviation, so it rewards strategies that are steady when falling and does not punish them for upside swings.
The Sharpe ratio uses total standard deviation, treating all volatility — up and down — as risk. The Sortino ratio uses only downside deviation, the volatility of returns below your target. For investors who don't mind big upside moves, Sortino is often the more meaningful measure.
Downside deviation is the standard deviation of only the returns that fall below a chosen target rate. It isolates the volatility that actually hurts you — the losing periods — and ignores periods where you outperformed the target.
As a rough guide, a Sortino ratio below 1 is weak, 1 to 2 is good, 2 to 3 is very good and above 3 is excellent. Because it excludes upside volatility, a strategy's Sortino ratio is usually higher than its Sharpe ratio.