Body Fat Estimate Calculator

Estimate adult body fat from BMI and age.

Your numbers

Updates as you type. Your values stay in your browser.

Your calculation
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Your calculation visualised

Calculation breakdown

Swipe sideways to see every column →

About this calculator

The Body Fat Estimate Calculator helps you Estimate adult body fat from BMI and age. Enter your own values to get an instant result, then use the graph and table to understand how the inputs affect the answer. Calculations run in your browser and are not sent to CalcifyNow.

How the calculation works

Enter BMI, Age, Sex used by formula. The calculator validates the inputs and updates the answer, chart and breakdown without sending your values to the server.

Formula and method

Uses the Deurenberg adult estimate. It is unsuitable for diagnosis, pregnancy, children or many athletes.

The result is recalculated whenever you change an input. Use consistent units throughout and keep the displayed rounding in mind when comparing with another source.

Worked example

Use the calculator's pre-filled values as a worked example:

  • BMI: 23
  • Age: 30
  • Sex used by formula: Male

Change one value at a time to see how it affects the result, graph and table.

How to interpret the result

Read the main result together with the supporting values. The graph shows the relationship visually, while the table makes each step easier to inspect.

Common uses

  • Understand a personal measurement or target.
  • Compare different inputs without saving personal data.
  • Use the estimate to prepare better questions for a qualified professional.

Limitations and common mistakes

This calculator cannot account for medical history, diagnosis, medication or every individual factor. It is informational and is not medical advice.

COMMON QUESTIONS

Frequently asked questions

What does the Body Fat Estimate Calculator calculate?

Estimate adult body fat from BMI and age.

What information do I need for the Body Fat Estimate Calculator?

Have these values ready: BMI, Age, Sex used by formula. Labels beside each field explain the expected unit or format.

How accurate is the Body Fat Estimate Calculator?

It applies the formula shown on this page. Its accuracy depends on the accuracy of your inputs and the assumptions described below the calculator.

How should I interpret the Body Fat Estimate result?

Treat the result as an informational estimate, not a diagnosis. Individual history and circumstances may change how a health measurement should be interpreted.

Can I use the Body Fat Estimate Calculator for an important decision?

Use it as an informed estimate, then confirm important decisions with current official information or a qualified professional.

Are my calculation inputs saved or shared?

No. The calculation runs locally in your browser. CalcifyNow does not submit your input values to its database.

Sources and review

Written byCalcifyNow Editorial Team