π² Portfolio Beta Calculator
Your portfolio\'s sensitivity to the market, in one number.
Weighted average of holding betas
Estimates for planning only, not financial advice.
Portfolio beta is the weighted average of your holdings' betas: how much your portfolio should move when the market moves 1 percent. A beta of 1.0 means you ride the market; 1.3 means 30 percent more swing; 0.7 means 30 percent less. Sixty percent in a 1.2-beta stock and 40 percent in a 0.7-beta stock gives a portfolio beta of exactly 1.0.
How to Use This Calculator
List each holding on its own line as weight percent, beta: for example "60, 1.2". Weights should total 100. Find betas on any quote page; use the same source for all holdings so the methodology matches. The calculator weights each beta and sums them.
Enter each holding's portfolio weight and beta, one per line, weights totaling 100 percent.
Read the weighted beta. Cash counts as zero beta and bonds near zero, so include them if they are part of the portfolio.
Decide if the risk fits your timeline. For return expectations at that risk, our average return calculator keeps score.
The Portfolio Beta Formula
Beta measures systematic risk only: the part of a stock's movement tied to the market. Diversifiable, company-specific risk is assumed away by diversification, which is why beta works best for diversified portfolios and poorly for three-stock gambles. A single-stock portfolio's beta understates its true risk badly.
Worked Example
You hold 60 percent in a tech stock with beta 1.2 and 40 percent in a utility with beta 0.7. Portfolio beta is 0.6 times 1.2 plus 0.4 times 0.7, which is 0.72 plus 0.28, totaling 1.00. The portfolio should track the market: up 10 percent when the market rises 10, down 10 when it falls 10. The aggressive and defensive holdings cancel precisely.
Reading Your Result
Match beta to your horizon and stomach. Long horizons can carry beta above 1.0 for higher expected returns; money needed soon usually wants beta below 1.0. But beta is backward-looking: it is estimated from past price co-movement, and the next crisis rarely repeats the last one's correlations.
My rule: beta tells you about the ride, not the destination. A high-beta portfolio is expected to earn more over decades, but the extra return is compensation for sickening drawdowns, and most investors overestimate their tolerance until they live through one. If you cannot hold through a 40 percent drop, do not own a 1.4 beta portfolio, whatever the spreadsheet says. For sizing positions so no single holding dominates that risk, keep weights deliberate and rebalanced. Our ROI calculator tracks whether the risk is actually paying.
Beta's practical value is position sizing, not prediction. A portfolio beta of 1.3 tells you to expect roughly 30 percent more movement than the market, up or down, which sets how much equity risk you actually hold. Rebalance when drift pushes beta away from target, recalculate betas yearly since they decay, and remember the fine print: beta describes the past relationship with the market, and relationships change.
Estimates for planning only, not financial advice.
Frequently Asked Questions
What is portfolio beta?
Portfolio beta is the weighted average of the betas of everything you own. It estimates how much your portfolio moves when the overall market moves 1 percent. A beta of 1.0 tracks the market; above 1.0 amplifies moves; below 1.0 dampens them.
How do you calculate portfolio beta?
Multiply each holding's portfolio weight (as a decimal) by its beta, then sum. For 60 percent at beta 1.2 and 40 percent at beta 0.7: (0.6 x 1.2) + (0.4 x 0.7) = 1.00. Rebalance quarterly: drift in weights silently changes your beta without a single trade.
What is a good portfolio beta?
It depends on your goals and timeline. Around 1.0 suits a long-term market-like return. Below 1.0 fits conservative investors or near-term goals. Above 1.0 fits aggressive long horizons. There is no universally right number, only the right number for your plan.
What beta do cash and bonds have?
Cash has a beta of zero; high-quality bonds sit near zero to 0.3. Including them pulls portfolio beta down, which is part of why balanced portfolios are calmer. Remember to include every asset, or the beta overstates your risk. A 60/40 stock-bond portfolio typically lands near 0.6 beta, which is the whole point of the blend.
Does beta measure total risk?
No, only systematic market risk. It ignores company-specific risk on the theory that diversification removes it. For a concentrated portfolio, total risk is much higher than beta suggests. Beta is most honest for well-diversified portfolios. Single-stock portfolios can have total volatility triple what beta implies: diversify first, fine-tune beta second.
Why do betas change over time?
Beta is estimated from historical price co-movement, usually two to five years of data. As a company's business, leverage, or investor base changes, its sensitivity to the market changes too. Recalculate periodically rather than trusting a stale number. Bloomberg's adjusted beta blends raw beta toward 1.0, assuming extremes fade over time.
Can portfolio beta be negative?
Yes, if you hold negatively-correlated assets like certain hedges, inverse funds, or gold in some periods. A negative-beta portfolio rises when markets fall. Most long-only portfolios sit between 0.5 and 1.5. Gold's beta hovers near zero long-term but spikes in crises, which is exactly when you want it.
What is the difference between beta and correlation?
Beta measures the magnitude of movement relative to the market; correlation measures how tightly movements track. A stock can be highly correlated but low beta (moves with the market, but less), or high beta with modest correlation. A beta of 1.5 with 0.9 correlation is a leveraged market tracker; with 0.3 correlation it is mostly noise.
How does leverage affect beta?
Borrowing to invest multiplies beta: 50 percent margin leverage roughly doubles portfolio beta. Leveraged ETFs reset daily, which makes their long-run beta drift from the advertised multiple. Treat leverage as a beta amplifier with compounding side effects. Leveraged ETFs are daily-reset instruments: holding them for months makes the stated multiple fiction.
Should I target a specific beta?
Use it as a guardrail, not a target. Decide your risk capacity first from goals and temperament, then check that your portfolio's beta is consistent with it. Rebalance when drift pushes beta away from where you want it. Risk parity funds invert this: they size positions so each asset contributes equal risk, not equal dollars.