Estimate body fat percentage using the Navy measurement method and BMI-based formula. Enter your bmi and get body fat % and category instantly — no spreadsheet required.
Step 1. Enter your bmi in the first field.
Step 2. Fill in age, sex to complete the required inputs.
Step 3. The calculator instantly shows Body Fat %, Category, Lean Mass Estimate based on the formula: Navy (Men): BF% = 86.010×log10(waist−neck)−70.041×log10(height)+36.76; Navy (Women): BF%=163.205×log10(waist+hip−neck)−97.684×log10(height)−78.387; BMI Method: BF%=1.2×BMI+0.23×Age−10.8×Sex−5.4.
With the default inputs loaded in the form, the calculator produces a starting result you can use as a baseline. Change one field at a time to compare a new scenario.
The Body Fat Calculator works by applying the formula: Navy (Men): BF% = 86.010×log10(waist−neck)−70.041×log10(height)+36.76; Navy (Women): BF%=163.205×log10(waist+hip−neck)−97.684×log10(height)−78.387; BMI Method: BF%=1.2×BMI+0.23×Age−10.8×Sex−5.4. Each input plays a distinct role — small changes to bmi can shift body fat % significantly, which is why running multiple scenarios before making a decision is valuable.
To use this calculator effectively, gather accurate values for Bmi, Age, Sex, Waist Or Neck Measurements. Estimates are fine for exploration, but the more precise your inputs, the more actionable the output. The calculator instantly returns Body Fat %, Category, Lean Mass Estimate, giving you a clear picture of where you stand.
This type of health calculation is commonly used in real planning scenarios — not just academic exercises. Whether you are comparing options, setting a target, or checking your current position, the Body Fat Calculator gives you a reliable number to work from. Always revisit the calculation if any input changes significantly.
It calculates body fat %, category, lean mass estimate using the formula Navy (Men): BF% = 86.010×log10(waist−neck)−70.041×log10(height)+36.76; Navy (Women): BF%=163.205×log10(waist+hip−neck)−97.684×log10(height)−78.387; BMI Method: BF%=1.2×BMI+0.23×Age−10.8×Sex−5.4. The inputs required are bmi, age, sex, waist or neck measurements.
You need: Bmi; Age; Sex; Waist Or Neck Measurements. Use accurate figures from your actual situation for the most useful result.
Results are mathematically precise given the inputs you provide. The formula used is: Navy (Men): BF% = 86.010×log10(waist−neck)−70.041×log10(height)+36.76; Navy (Women): BF%=163.205×log10(waist+hip−neck)−97.684×log10(height)−78.387; BMI Method: BF%=1.2×BMI+0.23×Age−10.8×Sex−5.4. Accuracy depends on how precise your input values are — estimates work for planning, but use exact figures for final decisions.
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Disclaimer: Results from this calculator are for informational and planning purposes only and do not constitute financial, legal, or professional advice. Always verify important calculations with a qualified professional.
