Portfolio Beta Calculator
Blend the betas of up to three holdings by weight to get your portfolio beta — how much it tends to move for a given market move.
How it works
Portfolio beta = Σ (weightᵢ × betaᵢ) ÷ Σ weights · Expected move ≈ beta × market move
Beta measures how much an asset tends to move relative to the overall market: a beta of 1 moves with it, above 1 amplifies its swings, and below 1 dampens them. A portfolio’s beta is simply the weighted average of its holdings’ betas, so mixing high- and low-beta assets lets you dial your overall market sensitivity up or down. Weights that do not add to 100% are normalised, so you can enter relative sizes and still get a valid blended figure.
Worked example
Three holdings at 50%, 30% and 20% with betas 1.2, 0.9 and 1.5: portfolio beta = (0.5 × 1.2 + 0.3 × 0.9 + 0.2 × 1.5) = 1.17. If the market rises 10%, the portfolio would be expected to rise about 11.7%.
Sources: Beta (finance) — Wikipedia
Frequently asked questions
What does a beta above 1 mean?
The holding tends to move more than the market: a beta of 1.2 suggests roughly a 12% move when the market moves 10%, in the same direction. Betas below 1 move less, and a negative beta tends to move opposite the market.
What if my weights do not add up to 100%?
The calculator divides by the total weight you enter, effectively normalising them. So entering 50/30/20 or 5/3/2 gives the same portfolio beta — only the relative proportions matter.
Does a low beta mean low risk?
Beta only captures market-related (systematic) risk. A stock can have a low beta yet carry large company-specific risks that beta does not see, so it is one lens on risk, not the whole picture.
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Educational estimate, not investment advice. Markets involve risk of loss.