How to Calculate Portfolio Risk - Portfolio Volatility & Standard Deviation Calculator
Learn how to calculate portfolio risk, volatility, and standard deviation with our free calculator and formula guide. Calculate portfolio volatility, standard deviation of portfolio, portfolio variance, and investment risk. Use our portfolio volatility calculator, standard deviation of portfolio calculator, and investment risk calculator to measure risk using Modern Portfolio Theory. Formula: σp = √(w₁²σ₁² + w₂²σ₂² + 2w₁w₂σ₁σ₂ρ). Our calculator helps investors assess portfolio risk using asset allocation analysis, correlation modeling, and risk-adjusted return calculations for optimal diversification strategies.
Last updated: February 2, 2026
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Asset Allocation (%)
Risk Parameters
Annual standard deviation (typical: 15-20% for stocks)
Annual standard deviation (typical: 4-8% for bonds)
Correlation between stocks and bonds (-1 to 1, typical: 0.1-0.3)
Risk Analysis
Risk Level
Moderate Risk
Portfolio Volatility
11.30%
annual standard deviation
Sharpe Ratio
0.37
Max Drawdown
28.2%
Diversification Benefit
1.30%
risk reduction from diversification
Analysis:
Balanced portfolio with appropriate risk-return profile.
Portfolio Risk Formula:
- • σp² = ws²σs² + wb²σb² + 2wswbσsσbρ
- • Lower correlation = better diversification
- • Sharpe Ratio = (Return - Risk-Free) / Volatility
- • Volatility measures portfolio uncertainty
How to Calculate Portfolio Risk - Step by Step Guide & Formula
Portfolio Risk Formula
Main Formula:
σp = √(w₁²σ₁² + w₂²σ₂² + 2w₁w₂σ₁σ₂ρ₁₂)
- • σp = Portfolio standard deviation
- • w₁, w₂ = Asset weights
- • σ₁, σ₂ = Asset volatilities
- • ρ₁₂ = Correlation (-1 to +1)
- • 60% stocks (18% vol)
- • 40% bonds (6% vol)
- • Correlation: 0.2
- • Portfolio Risk: 11.3%
Step-by-Step: How to Calculate Portfolio Risk
Step 1: Determine Asset Weights
Calculate the percentage allocation for each asset:
Weight = Asset Value ÷ Total Portfolio Value
Example: $60,000 stocks ÷ $100,000 total = 60% (w₁ = 0.60)
$40,000 bonds ÷ $100,000 total = 40% (w₂ = 0.40)
Step 2: Get Individual Asset Volatilities
Find standard deviation (volatility) for each asset:
- • Stocks: Typically 15-20% annual volatility
- • Bonds: Typically 4-8% annual volatility
- • Cash: 0% volatility
- • Convert percentages to decimals: 18% = 0.18
Step 3: Find Asset Correlations
Determine correlation coefficient between assets:
- • Range: -1 (perfect opposite) to +1 (perfect together)
- • Stocks-Bonds: Typically 0.1-0.3 (slightly positive)
- • Lower correlation = better diversification
- • Negative correlation = best diversification
Step 4: Calculate Portfolio Variance
Apply the variance formula:
σp² = w₁²σ₁² + w₂²σ₂² + 2w₁w₂σ₁σ₂ρ
Example: 0.6²×0.18² + 0.4²×0.06² + 2×0.6×0.4×0.18×0.06×0.2 = 0.0128
Step 5: Calculate Portfolio Standard Deviation
Take the square root of variance:
σp = √Variance
Example: √0.0128 = 0.113 = 11.3% portfolio risk
Portfolio Risk Calculation Example
Example: 60/40 Stock/Bond Portfolio
Key Insight: Portfolio risk (11.3%) is lower than the weighted average (13.2%) due to diversification. This demonstrates how combining assets with low correlation reduces overall portfolio risk.
Portfolio Risk Calculator Types & Investment Analysis Tools
Measures
Std Dev, Variance
Quantifies portfolio return uncertainty
Formula
(Return - RF) / σ
Evaluates returns relative to risk taken
Correlation
-1 to +1
Measures how assets move together
Asset Classes
Stocks, Bonds, Cash
Optimizes allocation for risk tolerance
Estimate
2-3× Volatility
Projects potential peak-to-trough losses
Concept
Efficient Frontier
Maximizes return for given risk level
Formula
σp = √(w₁²σ₁² + w₂²σ₂² + 2w₁w₂σ₁σ₂ρ)
Calculates portfolio volatility accounting for correlations
Risk metrics
Volatility, Sharpe Ratio
Comprehensive investment risk analysis
Quick Example Result
60/30/10 stocks/bonds/cash allocation with 18%/6% volatilities:
Portfolio Volatility
11.30%
Risk Level
Moderate Risk
How Our Portfolio Risk Calculator Works
Our portfolio risk calculator applies Modern Portfolio Theory to measure investment risk through volatility, correlation, and diversification analysis. The calculation uses variance-covariance methodology to determine portfolio risk metrics, helping investors optimize asset allocation for their risk tolerance and financial goals.
Portfolio Risk Formula - Complete Guide
Main Portfolio Risk Formula:
σp = √(w₁²σ₁² + w₂²σ₂² + 2w₁w₂σ₁σ₂ρ₁₂)Where: w = asset weights, σ = volatilities, ρ = correlation
Additional Formulas:
Portfolio Variance = w₁²σ₁² + w₂²σ₂² + 2w₁w₂σ₁σ₂ρSharpe Ratio = (Rp - Rf) / σpDiversification Benefit = Weighted Avg Vol - Portfolio VolQuick Calculation Example:
The calculator uses the variance-covariance method to compute portfolio volatility, accounting for individual asset risks and their correlations. Lower correlation between assets provides better diversification, reducing portfolio risk below the weighted average of individual asset risks—the fundamental insight of Modern Portfolio Theory.
Shows optimal portfolios balancing risk and return along the efficient frontier
Mathematical Foundation
Portfolio risk calculation is based on Modern Portfolio Theory developed by Harry Markowitz (Nobel Prize 1990). The theory demonstrates that portfolio risk depends not just on individual asset risks but critically on correlations between assets. Combining uncorrelated or negatively correlated assets reduces overall portfolio volatility—diversification is the only "free lunch" in investing. The efficient frontier represents optimal portfolios offering maximum return for each risk level, and the Sharpe ratio identifies the portfolio with best risk-adjusted returns.
- Portfolio volatility measures total portfolio return uncertainty
- Lower correlation between assets improves diversification
- Sharpe ratio evaluates returns relative to risk taken
- Maximum drawdown estimates worst-case decline scenarios
- Diversification reduces risk without sacrificing expected returns
- Optimal portfolios lie on the efficient frontier curve
Sources & References
- Portfolio Selection - Harry Markowitz (1952)Seminal paper introducing Modern Portfolio Theory
- The Intelligent Asset Allocator - William BernsteinPractical guide to portfolio construction and risk management
- CFA Institute - Portfolio Management StandardsProfessional standards for investment risk analysis
Need help with other investment calculations? Check out our investment growth simulator and retirement ROI calculator.
Get Custom Calculator for Your PlatformPortfolio Risk Examples
Portfolio Inputs:
- Stocks: 60% at 18% volatility
- Bonds: 30% at 6% volatility
- Cash: 10% at 0% volatility
- Stock-Bond Correlation: 0.2
Risk Metrics:
- Portfolio Volatility: 11.30%
- Undiversified Risk: 13.2%
- Diversification Benefit: 1.30%
- Sharpe Ratio: 0.37
Result: Moderate risk portfolio with moderate risk
Diversification reduces risk by 1.30% compared to undiversified portfolio. Expected max drawdown: approximately 28.2% during severe market downturns.
Conservative Portfolio
30/60/10 stocks/bonds/cash
Risk: ~7% volatility
Aggressive Portfolio
90/10/0 stocks/bonds/cash
Risk: ~17% volatility
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