The Sortino ratio refines the Sharpe ratio by measuring excess return against downside deviation only — volatility from returns above your target is excluded. For strategies with asymmetric payoffs like trend-following or options selling, this distinction produces dramatically different readings and often reverses which strategy appears safer.
How to Use
| Input | What to Enter | Example |
|---|---|---|
| Annualized Return | Your total portfolio return over the measurement period, annualized | 28% |
| Minimum Acceptable Return (MAR) | The return floor; use 0% for capital preservation or 5.25% for risk-free rate | 5.25% |
| Downside Deviation | Annualized standard deviation of sub-MAR monthly returns only | 7% |
The calculator outputs a single ratio. Compare it against the thresholds below: below 1.0 is underperforming on a risk-adjusted basis, 1.0–2.0 is acceptable for active traders, above 2.0 is strong, and above 3.0 is exceptional.
Formula Explained
Sortino Ratio = (Portfolio Return − MAR) / Downside Deviation
Downside Deviation = sqrt( mean( min(Return_i − MAR, 0)^2 ) ) × sqrt(12)
Portfolio Return is the annualized return over your measurement period — typically 12 months of live trading.
MAR (Minimum Acceptable Return) is the threshold below which a return period counts as underperformance. Setting MAR to 0% means any negative month penalizes the score; setting it to 5.25% (the approximate Fed Funds rate in 2024/2025) measures whether the strategy beats holding cash. The MAR choice is more consequential now than during the near-zero rate years of 2010–2021.
Downside Deviation captures only the distribution of returns below the MAR. For each month, subtract the MAR from the return; if the result is negative, square it. Average those squared values across all months, then take the square root. Multiply by the square root of 12 to annualize monthly figures. Months where the return exceeds the MAR contribute exactly zero to this calculation — their upside size is irrelevant.
This construction is why the Sortino ratio was developed by Frank Sortino in the early 1980s, explicitly to correct the Sharpe ratio (introduced by William Sharpe in 1966) for strategies where winning periods are large and lumpy.
Example Calculations
Scenario 1: ES Breakout Trend-Follower vs. SPY Put Spread Seller
Two traders both return 28% annualized over 12 months, measured against a 5.25% MAR.
Trader A — ES Breakout Strategy
- Wins average +$3,200, losses average −$900, 38% win rate
- Large winning trades spike total standard deviation to 29%
- Sharpe = (28% − 5.25%) / 29% = 0.79 — looks poor
- Only 4 of 12 months are negative, with small deficits; downside deviation = 7%
- Sortino = (28% − 5.25%) / 7% = 3.25 — exceptional
Trader B — SPY Put Spread Seller
- 8 of 12 months are small wins (+1–3%), but two months blow up at −14% and −11%
- Consistent small wins keep total standard deviation at 11%
- Sharpe = (28% − 5.25%) / 11% = 2.09 — looks excellent
- Those two blow-up months drive downside deviation to 18%
- Sortino = (28% − 5.25%) / 18% = 1.26 — adequate, but the tail risk is exposed
Same annual return. Sharpe ranks Trader B as more than twice as efficient as Trader A. Sortino ranks Trader A as 2.6× safer. The Sharpe ratio is penalizing Trader A for big wins; the Sortino ratio ignores those wins entirely and focuses on the actual loss months.
Scenario 2: Conservative Swing Trader
- 12-month return: 18%, MAR: 0% (capital preservation goal), downside deviation: 8%
- Sortino = 18% / 8% = 2.25 — strong
Using a 0% MAR rather than the risk-free rate raises the score by excluding the risk-free hurdle, making this the appropriate setting for traders focused on avoiding drawdowns rather than beating cash.
When to Use the Sortino Ratio
- Evaluating trend-following systems: Large winning trades inflate standard deviation in Sharpe but are correctly ignored by Sortino. Top trend-following CTAs historically post Sortino ratios of 0.5–2.0 despite Sharpe ratios of only 0.3–0.8 — both numbers are correct, but Sortino better represents the actual experience of holding the strategy.
- Auditing options premium-selling strategies: Consistent small credits can produce a high Sharpe while masking catastrophic tail months. Sortino forces those blow-up months into the denominator, revealing the real risk profile.
- Comparing strategies with different return distributions: When two strategies have similar annualized returns, Sortino is the cleaner tool for determining which one achieves those returns with less painful drawdown.
- Tracking improvement in a trading journal: Use monthly Sortino alongside maximum drawdown to confirm that improvements to win rate or expectancy are not coming at the cost of worsening tail risk.
- Prop firm evaluation context: While many funded account programs use Sharpe or Calmar in their dashboards, calculating your own Sortino provides a second opinion on whether your edge is genuinely robust or dependent on conditions that suppress downside volatility.
Related Tools
- Sharpe Ratio Calculator — Calculates risk-adjusted return using total standard deviation; run alongside Sortino to see how much upside volatility is distorting your Sharpe reading.
- Expectancy Calculator — Computes average expected profit per trade from win rate and average win/loss; use this to understand why a trend-following system with a low win rate can still generate a high Sortino.
- Max Drawdown Calculator — Measures the worst peak-to-trough equity decline; pairs with Sortino to give a complete picture of downside risk from both a deviation and an absolute-loss perspective.
Frequently Asked Questions
How do I calculate the Sortino ratio from my trade journal?
Pull monthly returns from your journal. For each month, subtract your MAR (use 0% if unsure). Keep only the negative results, square each one, then average all the squared values — including the zero contribution from months above MAR. Take the square root and multiply by the square root of 12 to annualize. Divide your annualized return minus MAR by that figure. JournalPlus computes this automatically from your trade history.
Why does the Sortino ratio matter more than the Sharpe ratio for trend-following?
Trend-following strategies generate returns through infrequent large wins, which creates high total standard deviation even when losing months are small. Sharpe penalizes that upside volatility as if it were risk, artificially suppressing the score. Sortino measures only the months that actually hurt capital. A breakout ES futures strategy returning 38% with only 4 negative months and 9% downside deviation produces a Sortino of 3.67 — elite — while its Sharpe of 1.06 looks merely average.
What MAR should active stock traders use?
Most active traders use either 0% (no capital should be lost) or the current risk-free rate (5.25% in 2024/2025, representing the opportunity cost of not being in a money market fund). Using the risk-free rate produces a more conservative and intellectually honest Sortino score. If your strategy cannot beat the risk-free rate on a downside-deviation-adjusted basis, that is relevant information.
Is a higher Sortino ratio always better?
A higher Sortino is better all else equal, but an extremely high ratio from a short track record should be treated with skepticism. A strategy with only 3 negative months over 24 months may have very low downside deviation simply because it has not yet encountered the market conditions that trigger its losses. The ratio is most reliable over full market cycles that include both trending and mean-reverting environments.
How does the Sortino ratio handle strategies with no losing months?
If no monthly return falls below the MAR, downside deviation equals zero and the Sortino ratio is undefined — effectively infinite. This happens with some options premium-selling strategies during prolonged low-volatility bull markets. The infinite reading is not a signal of safety; it reflects an absence of data about downside behavior. The risk of ruin calculator is a better tool for stress-testing strategies in this situation.
