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Full Body Fat calculatorEstimates for education and orientation — not medical advice or a diagnosis.
Understanding body composition
A scale measures one thing: total mass. That mass is fat tissue plus everything else — muscle, bone, organs and water, together called lean or fat-free mass. Two people can weigh exactly the same and have very different bodies, because what the weight consists of differs.
This is why weight alone gives limited information. Losing two kilograms of fat while gaining two kilograms of muscle leaves the scale unchanged — yet the body, its shape and its metabolism have clearly changed. Body fat percentage, lean mass and waist-to-hip ratio exist to describe that difference.
The practical approach is to track composition alongside weight, using the same measurement method each time, and to read trends over weeks rather than single readings.
Understand your body metricsUnderstanding your daily energy needs
Your basal metabolic rate (BMR) is the energy your body spends at complete rest — breathing, circulation, temperature regulation, cell repair. For most adults it accounts for the majority of the day's energy use, even before any deliberate movement.
Total daily energy expenditure (TDEE) adds everything else on top: walking, working, training and fidgeting. The gap between the two is set by your activity level, which is why the same person can need 2,000 kcal in a sedentary week and 2,700 kcal in an active one.
Both figures come from population equations — Mifflin–St Jeor for BMR, multiplied by an activity factor for TDEE. They are starting points to be checked against your actual weight trend, not personal measurements.
Estimate your BMR and TDEEMan, 30 years · 80 kg · 180 cm
Mifflin–St Jeor estimate. Individual metabolism can differ by ten percent or more in either direction.
Nutrition, protein and macronutrients
Everything you eat provides energy through three macronutrients. Protein and carbohydrate give 4 kcal per gram; fat gives 9. A daily calorie target says how much energy to eat — the macro split says where that energy comes from.
Protein deserves attention first because it does double duty: it builds and preserves muscle, and it keeps you full. Needs scale with body weight and goal — from the 0.8 g/kg reference intake for general health up to roughly 1.6–2.2 g/kg for muscle gain or fat loss with training. Fat covers hormonal function and nutrient absorption, and carbohydrate fills the remaining energy, fuelling training and daily activity.
Needs differ between people because body weight, muscle mass, training load and goals differ. That is why generic advice like "eat 50% carbs" is less useful than a split built from your own calorie target and weight — and why no split can rescue a calorie target that does not match your actual expenditure.
Maintenance split at 2,200 kcal per day
A general framework split, not an individual dietary prescription.
Why estimates are not diagnoses
Every number on this site is one of three things: a calculation from a fixed formula, an estimate from a population-derived equation, or a reference range published for groups of people. None of them is a measurement of your body, and none is a medical assessment.
Population equations are built from averages across many people. They are useful precisely because they give a reasonable starting point for almost anyone — and limited for the same reason, because no individual is an average. A tape-measure body fat estimate can differ from a DXA scan by several percentage points; a TDEE estimate can miss your real expenditure by hundreds of calories.
The right way to use these tools is as orientation: compare like-for-like measurements over time, watch trends, and bring persistent concerns or unexplained changes to a healthcare professional.
Estimate your body fatU.S. Navy body-fat estimate
19.8%
Acceptable · ACE reference classification
A tape-measure estimate, not a scan. Reference categories are not medical diagnoses or universal targets. Typical error is several percentage points.
Learn how to use our calculators effectively and understand the science behind your health metrics.
Body Composition
Body fat percentage is a more accurate indicator of health than weight alone. Learn what the numbers mean, healthy ranges, and how to measure yours accurately.
Nutrition
Your TDEE is the total number of calories you burn each day. Understanding this number is crucial for weight loss, muscle gain, or maintaining your current weight.
Nutrition
Protein is essential for building muscle and supporting recovery. Explore the best sources, learn meal timing strategies, and find the right supplements for your goals.
Quick answers to common questions about our health calculators
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