Body Fat Percentage Calculator

About Body Fat Percentage Calculator

Estimate body fat percentage using the U.S. Navy method. This calculator provides instant results with step-by-step explanations to help you understand the calculation process.

How to use this calculator

1. Measure your waist, neck, and height carefully in the same unit, usually inches.
2. Enter the values into the calculator so it can apply the U.S. Navy formula.
3. Read the estimated body fat percentage and use it as a guide, not a medical diagnosis.

The formula explained

• \(Body Fat %\) = estimated body fat percentage
• \(\text{waist}\) = waist circumference in inches
• \(\text{neck}\) = neck circumference in inches
• \(\text{height}\) = height in inches
• \(log10\) = base-10 logarithm

Step by step method

1. Measure waist, neck, and height accurately, keeping the tape level and snug but not tight.
2. Use the U.S. Navy equation with the difference between waist and neck, plus the height value.
3. Calculate the logarithms and combine the terms in the denominator.
4. Compute \(\frac{495}{\text{result}} - 450\) to get the estimated body fat percentage.

Worked example

For example, suppose a person has a 34 inch waist, 15 inch neck, and 70 inch height.

1. First find the waist minus neck value: \(34 - 15 = 19\).
2. Compute the denominator: \(1.0324 - 0.19077\log_{10}(19) + 0.15456\log_{10}(70)\). Using \(\log_{10}(19) \approx 1.279\) and \(\log_{10}(70) \approx 1.845\), this is about \(1.0324 - 0.19077(1.279) + 0.15456(1.845) \approx 1.084\).
3. Now calculate \(\frac{495}{1.084} - 450 \approx 456.6 - 450 = 6.6\).

Tips and common mistakes

• Use the same unit for every measurement, and inches are the standard for this formula.
• Measure at the same body locations each time so results are more consistent.
• This is an estimate, so small changes in tape placement can affect the result.
• If the result seems unusual, double-check the measurements before trusting the number.

Frequently asked questions