Body Fat Calculator
Estimate body fat percentage using the US Navy method.
How this calculator works
Formula
US Navy tape method using height, neck, waist (and hip for women)
Method
Empirical formula validated against hydrostatic weighing.
Example
Man 178 cm, waist 85 cm, neck 40 cm ≈ 15% body fat.
The complete guide to the Body Fat Calculator
Estimate body fat percentage using the US Navy method. This guide covers exactly what Body Fat Calculator computes, the formula behind it, a worked example, and the mistakes that most often produce a wrong number.
How the calculation works
Empirical formula validated against hydrostatic weighing. Each input feeds directly into that model, so changing one value shows its isolated effect on the result.
The formula
The core equation is US Navy tape method using height, neck, waist (and hip for women). Working it by hand follows the same order of operations; the risk is arithmetic slips and rounding at intermediate steps, which the tool avoids by keeping full precision until the final display.
A worked example
Man 178 cm, waist 85 cm, neck 40 cm ≈ 15% body fat. Enter those values above to confirm the result, then vary one input at a time to see which variable moves the outcome most.
When this calculator is the right tool
Use Body Fat Calculator for planning, comparison and verification — cases where the arithmetic is tedious enough that manual errors are likely, or where you want several scenarios side by side rather than a single answer.
Common mistakes to avoid
The most frequent error is a unit mismatch — annual instead of monthly figures, or the wrong measurement unit. Read the label above each field. The second is treating a single result as certain: when the number drives a real decision, re-run it with slightly more conservative assumptions and see how far the answer moves.
Reading the result critically
A result is only as good as its assumptions. Identify which input carries the most uncertainty, test a realistic worst case for it, and use the gap between the two outcomes as your planning margin rather than the headline figure alone.
Frequently asked questions
What does Body Fat Calculator calculate?
Estimate body fat percentage using the US Navy method.
How accurate is the result?
The calculation uses the standard formula for this problem, so accuracy is limited only by the accuracy of your inputs and any assumptions the model makes.
Which input affects the result most?
Change one input at a time and watch the result. The variable that moves the outcome most is where you should focus your estimate.
Can I compare several scenarios?
Yes — adjust the inputs and note each result, or use the comparison and history features where the calculator offers them.