Health Calculators
Use this body fat calculator to estimate body fat percentage from height, weight, neck, waist, and hip measurements in pounds/inches or kilograms/centimeters.
Live calculator
U.S. Navy circumference-style estimate from tape measurements.
110.7 lb estimated lean mass.
Formula still uses the converted 66 in / 167.6 cm height and in/lb inputs.
Tape-measure formulas can move a lot when measurements change by even a small amount. Use consistent measurement points and treat the result as a tracking estimate, not a clinical body composition test.
Use this as a planning estimate, not medical advice. Medical conditions, medication, pregnancy, eating disorder history, or disease-specific nutrition needs should be handled with a qualified professional.
Quick answer
Body Fat Calculator calculates estimated body fat from sex, weight, height, neck, waist, hip, and other visible inputs. The visible formula is Men: 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76; women: 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387.
Formula
Men: 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76; women: 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387The equation uses inches internally. Metric inputs are converted to inches before calculation, and tape estimates remain sensitive to measurement technique.
How to use
Example
Calculator use
Before relying on it
Details
These notes make the assumptions explicit, especially where the same search query can mean slightly different things.
Small tape-measure differences can shift the result, so use consistent landmarks, the same unit system, and a non-stretch tape.
This is not the same as DEXA, hydrostatic weighing, or a clinical body composition assessment.
The result is most useful when you measure the same way over time rather than treating one estimate as exact.
Source notes
Benchmarks
The calculator is a decision aid, not a fixed rule. Use the output to compare scenarios and document your assumptions. Benchmark ranges are broad planning heuristics unless this page names a specific source for the range.
Easy to repeat at home, but less precise than clinical body composition tests.
May be useful when accuracy matters for medical or athletic decisions.
Consistent repeated measurements are usually more useful than a single estimate.
Calculator accuracy
The formula, inputs, example, and limitations are shown so the result is checkable, not just a number in a box.
Men: 86.010 x log10(waist - neck) - 70.041 x log10(height) + 36.76; women: 163.205 x log10(waist + hip - neck) - 97.684 x log10(height) - 78.387
Sex, Weight, Height, Neck, Waist, Hip, Unit system
Health results are screening or planning estimates. Age, body composition, medication, medical history, pregnancy, and professional guidance can change the right interpretation.
June 6, 2026
Toolkit Shelf. Body Fat Calculator. Last reviewed June 6, 2026. https://toolkitshelf.com/tools/body-fat-calculator
FAQ
It applies a U.S. Navy-style circumference equation using height and tape measurements from the neck, waist, and hips. Metric inputs are converted to inches for the formula.
No. Tape-based body fat is an estimate and can change with measurement technique, hydration, posture, and body shape.
The common U.S. Navy-style female equation uses waist, hip, neck, and height, while the male equation uses waist, neck, and height.
Ask a clinician or qualified nutrition professional when pregnancy, medication, medical history, eating disorder risk, symptoms, or disease-specific guidance matters.
Health formulas simplify age, sex, body composition, training status, measurement method, pregnancy, and medical context into a planning estimate.
No. Health calculators are screening or planning tools and do not diagnose, treat, or replace professional medical or nutrition guidance.