Body Fat Percentage Calculator

Estimate your body fat percentage with the US Navy formula or a BMI-based equation. Switch between imperial and metric units, then view body fat %, fat mass, lean mass, and your category on the visual scale.

Calculation Method

Units

Gender

Weight

lbs

Height

Neck circumference

Waist circumference

Hip circumference is only used for the female US Navy formula.

Body fat percentage

17.5%

Fat mass

31.5 lbs

Lean mass

148.5 lbs

How this calculator works

What this page estimates

This Body Fat Percentage Calculator is built to give a quick, browser-based estimate for body fat percentage. Estimate your body fat percentage with the US Navy formula or a BMI-based equation. Switch between imperial and metric units, then view body fat %, fat mass, lean mass, and your category on the visual scale. The inputs stay on the page during normal use, and the result should be treated as an estimate for planning, comparison, or education rather than professional advice.

Calculation approach

The calculator applies the standard relationship implied by the inputs, then formats the answer so it can be checked and reused. For general tools, the most important step is using consistent units, rates, time periods, and assumptions before comparing the result with another calculator or outside quote.

Example workflow

For example, start with a realistic value you already know, change one input at a time, and watch how the answer moves. That makes it easier to tell whether the result is being driven by the main amount, the rate, the time period, or a unit conversion.

Practical checks

Use current, real-world numbers when the result affects money, health, tax, or legal decisions.
Run a low, base, and high case when the inputs are estimates.
Check the related calculators below when the next decision depends on a different assumption.

How to interpret the body fat percentage result

Best use

Use the result as a practical estimate for comparing alternatives, checking a scenario, or deciding what to calculate next.

Cross-check

Compare the answer with the real document, measurement, source, or expert guidance that controls the final decision.

Watch for

The most common errors come from stale inputs, mismatched units, and assumptions that are too optimistic for the situation.

This page belongs to the planning calculator library, so the answer should be read in the context of the decision you are modeling rather than as a universal rule.

Before relying on this body fat percentage estimate

Most calculator mistakes come from the inputs, not the arithmetic. Use this short audit before you reuse the answer in a spreadsheet, quote, application, or important conversation.

Check input quality

Use current numbers, consistent units, and the same assumptions you plan to use outside the calculator.

Compare against a source

Match the result against the real document, measurement, quote, record, or expert guidance behind the decision.

Stress-test the result

Change the most uncertain input and see whether the answer still supports the same conclusion.

Rerun this page when the source numbers, units, timing, or assumptions change.

How to Use

Choose the US Navy method for circumference-based body fat estimates, or switch to BMI Estimate for a faster formula-based estimate.
Select imperial or metric units, then enter your gender, height, and weight.
For the Navy method, add neck and waist measurements, plus hip measurement if you select female.
For the BMI estimate, enter your age and either auto-calculate BMI from height and weight or type your BMI manually.
Review your body fat percentage, fat mass, lean mass, category, and the visual range indicator instantly.

Frequently Asked Questions

What is a healthy body fat percentage?

Healthy body fat ranges vary by sex and goals. For men, roughly 14% to 24% is often considered a normal range, while for women it is about 21% to 31%. Athletes are often lower, and essential fat levels are the minimum needed for basic physiological function.

Is the US Navy body fat method accurate?

The US Navy method is a widely used estimate based on circumference measurements. It is generally more informative than weight alone, but it can still be off depending on body shape, measurement technique, and how tightly you measure.

How is the BMI-based body fat estimate different?

The BMI-based estimate uses BMI, age, and sex to predict body fat percentage. It is quick and useful for broad screening, but it is less personalized than circumference or skinfold methods and can misread very muscular or very lean people.

Why do women need a hip measurement for the Navy method?

The female US Navy equation includes hip circumference because fat distribution patterns differ by sex. That extra measurement helps improve the estimate for women compared with using neck and waist alone.

Can I use body fat percentage to track progress?

Yes. Body fat percentage is often more useful than body weight by itself because it helps distinguish fat loss from changes in lean mass. For best results, measure under similar conditions each time and focus on trends instead of tiny day-to-day changes.