CAPM Calculator Guide: Expected Return, Beta & Limitations
CAPM maps systematic risk (beta) to a required or expected return above the risk-free rate. This guide states the formula, walks a numeric example, and flags where linear beta breaks down.
CAPM Calculator Guide: Expected Return, Beta & Limitations
Updated May 2026 · ~8 min read
CAPM estimates a required return from a selected risk-free rate, beta, and market risk premium. Each input depends on currency, horizon, benchmark, frequency, sample, leverage, and methodology. The result is not a realized-return forecast.
When CAPM is a reasonable starting point
- Cost of equity sketches: you need a single discount rate anchored to traded markets for comparable firms.
- Classroom or boardroom alignment: stakeholders expect beta-and-premium vocabulary even when models disagree.
- Sanity ranges: you check whether implied returns sit near peers before trusting a valuation.
- Not for timing: CAPM does not predict next month’s price—beta estimates are backward-looking.
The formula
Required return = Rf + β × market risk premium
Use compatible currency and horizon. Historical and forward-looking premium estimates are not interchangeable without explanation.
A conditional required-return estimate
Document beta source, benchmark, window, frequency, leverage treatment, and premium method.
Common mistakes
- Treating beta as permanent.
- Mixing currencies or horizons.
- Using historical return as a guaranteed premium.
- Treating CAPM output as a forecast.
Try the calculator
Use the interactive calculator to plug in your numbers and see results instantly—without redoing the math by hand.
Open CAPM calculator →FAQ
Which beta should I use?
Use a documented methodology appropriate to the decision.
Is CAPM expected return guaranteed?
No. It is a model-based required-return estimate.
Can other models differ?
Yes. Different factor and country-risk models can produce different estimates.
Related calculators
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Move from this guide into a complete calculator path with related tools and glossary terms.
Open the Risk & Portfolio hub →Educational Disclaimer
This article is for educational and informational purposes only and should not be considered investment, financial, tax, or legal advice. Market information may change over time, and readers should verify important details independently before making financial decisions.