Fat Mass Index (FMI) Calculator

kg
%
cm
Health Updated 14 Jun 2026

Fat Mass Index (FMI) Calculator is a health and wellness calculator that helps you calculate fat mass index (fmi) values from your input data. The formula used is: FMI = fat mass (kg) / height (m)², where fat mass = weight × body fat % / 100. Enter values using the units shown next to each input field (e.g. kg, cm, years).

  • Depends on the accuracy of the body fat percentage entered.

Formula

FMI = fat mass (kg) / height (m)², where fat mass = weight × body fat % / 100
  • Fat Mass Index (FMI) Calculator gives you a fast estimate using your inputs and updates instantly when you change any value.
  • Formula: FMI = fat mass (kg) / height (m)², where fat mass = weight × body fat % / 100
  • Input definitions: • Weight: the numeric weight used in the calculation • Body Fat: the numeric body fat used in the calculation • Height: the numeric height used in the calculation
  • Manual method: write down each input, apply the formula step by step, then compare your manual result with the calculator output.
  • Enter values using the units shown next to each input field (e.g. kg, cm, years).
  • This calculator uses widely accepted health formulas and returns screening estimates only. It does not replace a diagnosis from a qualified healthcare professional.
  • Compare your result with published reference ranges. Values outside the normal range warrant a conversation with your doctor.
  • Practical tip: test a low, medium, and high scenario to understand sensitivity before making decisions.

Example Calculation

Inputs
  • Weight: 75 kg
  • Body Fat: 20 %
  • Height: 175 cm

Suppose you enter: Weight = 75, Body Fat = 20, Height = 175. The calculator applies the formula (FMI = fat mass (kg) / height (m)², where fat mass = weight × body fat % / 100) and shows all output values below. Change any input field to immediately see how the result changes.

Frequently asked questions

What is the Fat Mass Index (FMI)?
The Fat Mass Index (FMI) Calculator is a health and wellness calculator that helps you calculate fat mass index (fmi) values from your input data. Enter values using the units shown next to each input field (e.g. kg, cm, years).
When should I use this calculator?
Use this calculator whenever you need a quick, accurate result for fat mass index (fmi) values from your input data without working through the arithmetic manually.
What units should I enter?
Enter values using the units shown next to each input field (e.g. kg, cm, years).
How accurate are the results?
This calculator uses widely accepted health formulas and returns screening estimates only. It does not replace a diagnosis from a qualified healthcare professional.
How do I interpret the result?
Compare your result with published reference ranges. Values outside the normal range warrant a conversation with your doctor.
How can I verify the calculation manually?
Use the displayed formula and work through the numbers step by step. If your manual result differs slightly, check rounding and unit conversions first.
Can I use this for planning and budgeting?
Yes. Run best-case, expected, and worst-case inputs to compare outcomes and make safer planning decisions.

Related calculators

Lean Mass Index (LMI) Calculator Lean Mass Index (LMI) Calculator is a health and wellness calculator that helps you calculate lean mass index (lmi) values from your input data. The formula used is: LMI = lean mass (kg) / height (m)², where lean mass = weight × (1 − body fat % / 100). Enter values using the units shown next to each input field (e.g. kg, cm, years). FFMI Calculator FFMI Calculator is a health and wellness calculator that helps you calculate ffmi values from your input data. The formula used is: Lean Mass (kg) = Weight × (1 − Body Fat %/100)\nFFMI (raw) = Lean Mass / height(m)²\nFFMI (normalised) = FFMI_raw + 6.1 × (1.8 − height_m). Enter values using the units shown next to each input field (e.g. kg, cm, years). Body Fat Calculator Popular Estimate your body fat percentage with the US Navy circumference method. Enter your sex, height, and a few tape measurements to see your body fat percentage, category, and healthy range.