Beta of Portfolio Calculator
One Number for How Sensitive a Whole Portfolio Is to the Market
Individual stocks each carry their own beta — a measure of how much they tend to move for every 1% move in the broader market. A portfolio holding several of them doesn't have an obvious combined beta until the individual figures are weighted by how much money sits in each position. This calculator does that weighting, turning a list of holdings into a single figure that describes the portfolio's overall market sensitivity.
The Formula
Portfolio beta is the weight-weighted sum of each holding's individual beta, after weights are normalized to sum to 100%:
Weights can be entered in any consistent unit (dollars, shares, or percentages) — the calculator normalizes them by dividing each weight by the total before applying it, so only the relative proportions matter.
Where This Matters
- Gauging market risk — a portfolio beta above 1 means the portfolio is expected to amplify market swings; below 1 means it should dampen them.
- Rebalancing toward a target risk level — investors targeting a specific beta can see exactly how adding or trimming a position shifts the combined figure.
- Comparing funds — two portfolios with the same headline return can carry very different betas, meaning very different amounts of market risk were taken to get there.
| Holding | Weight | Beta | Weighted contribution |
|---|---|---|---|
| Holding 1 | 40% | 1.20 | 0.480 |
| Holding 2 | 30% | 0.80 | 0.240 |
| Holding 3 | 30% | 1.50 | 0.450 |
| Portfolio Beta | 1.17 | ||
A portfolio beta of 1.17 implies roughly 17% more sensitivity to broad market moves than the market itself, in either direction.
How to Use This Calculator
- Enter the weight of each holding, comma-separated, in the order you'll list betas (e.g.
40,30,30). - Enter the beta of each corresponding holding, comma-separated (e.g.
1.2,0.8,1.5). - Select Calculate to get the normalized weight of each holding and the combined portfolio beta.
Related Calculations
Pair this with the CAPM Calculator to translate a portfolio's beta into an expected return, or the Treynor Ratio Calculator to see how that market risk is being compensated.