Sharpe Ratio Calculator
The Sharpe ratio, introduced by Nobel laureate William F. Sharpe in 1966, measures how much excess return a portfolio earns per unit of total risk taken. Enter the annualised portfolio return Rp, the same-period risk-free rate Rf and the annualised standard deviation σ to instantly see the Sharpe value, excess return and a rating against the widely cited 0 / 1 / 2 / 3 thresholds (poor / subpar / acceptable / good / excellent).
Sharpe ratio
0.90
Subpar
Excess return (Rp − Rf): +9.00%
Rating bands
Use Rp, Rf and σ measured over the same period and on the same annualisation basis (monthly figures × √12 to annualise).
Formula
Sharpe Ratio = (Rp − Rf) / σp
- · Rp = annualised portfolio return; Rf = same-period risk-free rate (e.g. short Treasury yield); σp = annualised standard deviation of portfolio returns.
- · Common practitioner buckets: < 1 subpar, 1–2 acceptable, 2–3 good, ≥ 3 excellent. Negative values mean the portfolio underperformed the risk-free asset.
- · All three inputs must share the same horizon and annualisation. From monthly figures, multiply the stdev by √12 (and the average monthly excess return by 12) before plugging in.
- · The ratio assumes returns are roughly normal — it understates fat-tail risks such as 2008. Pair it with Sortino, Calmar or maximum-drawdown metrics for a fuller picture.
- · Short windows (< 36 months) can produce misleadingly high or low Sharpe values; 3–5 years of data is the usual minimum for meaningful comparisons.
- · Reference: Sharpe, W. F. (1966) “Mutual Fund Performance,” Journal of Business; CFA Institute Investment Performance Measurement curriculum.
Frequently asked
What counts as a “good” Sharpe ratio?
Industry rules of thumb: ≥ 1 is acceptable, ≥ 2 is good, ≥ 3 is excellent. Over long horizons, broad equity indices (S&P 500) sit around 0.4–0.6; well-diversified balanced portfolios are typically 0.5–0.8; top hedge funds and long-running endowments may reach 1–2, with very few breaking 3 over short windows. A negative Sharpe means the portfolio earned less than a Treasury bill — you took risk and were not rewarded.
Which risk-free rate should I use?
Use the yield of a same-period, same-currency short-dated government instrument — for example a 3-month US T-Bill, a 91-day Hong Kong EFBN, or the lowest-risk savings rate available. Match the horizon to Rp: if Rp is a 5-year annualised figure, use the average short-rate over the same 5 years rather than today's spot yield. When Rf is low Sharpe figures look artificially high; when rates rise, Sharpe naturally compresses.
How does Sharpe differ from Sortino or the Information Ratio?
All three are risk-adjusted return measures, but they differ: (1) Sharpe uses total volatility (upside + downside) as the denominator; (2) Sortino divides only by downside deviation, since investors arguably only fear losses, not gains; (3) Information Ratio replaces Rf with a benchmark return Rb and divides by the tracking error, measuring how reliably an active manager beats their benchmark. Performance reports often quote all three together.
How do I annualise daily or monthly figures?
Use the “square-root-of-T” rule: multiply the period Sharpe by √(periods per year). Monthly × √12 ≈ × 3.464; daily (trading) × √252 ≈ × 15.87; weekly × √52 ≈ × 7.21. This assumes returns are independent and identically distributed; if returns are autocorrelated (momentum or mean-reversion), the simple rule slightly over- or understates the true annual Sharpe — Lo (2002) gives an autocorrelation-adjusted version for stricter use.
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