ARIA

Free ToolNo signup required

Volatility Calculator

Turn a series of returns into a per-period and annualised volatility — the standard measure of risk.

Standard Deviation

The spread of returns around their average

Annualised

√time scaling from daily, weekly, or monthly data

Paste Your Series

Works with any list of periodic percentage returns

Volatility From a Return Series
Paste a series of periodic returns (%) and pick how often they were measured. We compute the standard deviation per period and scale it up to an annualised volatility.

Comma- or space-separated. Each value is one period’s percentage return.

Used to annualise (multiply the std dev by the square root of the periods per year).

How Volatility Works

The Formula

σ = √[ Σ(rᵢ − r̄)² / (n − 1) ]
σ annual = σ × √(periods/yr)

Take the standard deviation of the periodic returns, then scale it to a year with the square-root-of-time rule. Daily data uses √252, weekly √52, monthly √12.

Risk, in One Number

Annualised volatility is the most widely quoted measure of risk and the denominator of risk-adjusted ratios. It feeds directly into the efficient frontier and the Markowitz optimisation that sits behind modern portfolio theory.

Full Portfolio Analytics

Want your real portfolio’s volatility?

ARIA measures the annualised volatility of your whole portfolio from live holdings — accounting for how every position co-moves, not just one asset at a time.

Create Free Account

Related Free Tools

Variance Calculator
The squared version of volatility — sample and population.
Covariance Calculator
How two assets’ returns move together.
Correlation Calculator
Standardise covariance to a −1 to +1 scale.
Efficient Frontier Calculator
Combine return and volatility into a risk-return curve.
Calmar Ratio Calculator
Return per unit of maximum drawdown.
Portfolio Calculator
Analyse allocation, concentration, and weighted return.
Sector Allocation Calculator
See your portfolio’s sector weights and concentration.

Frequently Asked Questions