Covariance Calculator

Free ToolNo signup required

Find the covariance and correlation between two assets — the basis of diversification.

Sample & Population

Both the n − 1 and n versions in one go

Correlation Too

The standardised −1 to +1 version alongside

Paste Your Series

Works with any two equal-length lists of numbers

Covariance Between Two Assets

Paste two equal-length series of returns (or any paired values) to find their covariance and correlation.

How Covariance Works

The Formula

Cov(X,Y) = Σ (xᵢ − x̄)(yᵢ − ȳ) / (n − 1)

Each pair contributes the product of its two deviations from the mean. Sum them and divide by n − 1 (sample) or n (population). A large positive sum means the assets rise and fall together.

The Engine of Diversification

Portfolio variance depends on the covariances between holdings, not just their individual volatilities. Pairing assets with low or negative covariance is what lets a portfolio achieve lower risk than its parts — the core insight behind Markowitz optimisation.

Full Portfolio Analytics

Want deeper insights?

ARIA builds the full covariance matrix across your holdings to measure true portfolio risk and optimise diversification — far beyond a single pair of assets.

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