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Body Composition Calculators, Guides & Benchmarks
Body composition gives you a better baseline than scale weight alone because it separates fat mass from fat-free mass. That matters whether you are cutting, maintaining, or trying to add muscle without losing sight of health markers. BMI can be a fast screen, but it misses where weight comes from; body-fat estimates, lean body mass, FFMI, and waist-to-hip ratio add context about muscularity, fat distribution, and trend quality over time. None of these metrics should be treated as a perfect truth in isolation. The practical move is to compare multiple measures, watch long-term direction, and use the data to set more realistic physique, recomposition, and weight targets.
Body Composition
Guides & Content
31
Related Topics
1
Tools In This Category
Run the numbers that matter here
These calculators and planners cover the core inputs, benchmarks, and tradeoffs behind body composition decisions.
Body Composition Calculator
BMI Calculator
BMI calculator: calculate body mass index quickly and interpret the result with a body-neutral range context.
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Body Composition Calculator
Body Fat Percentage Calculator
Estimate body fat percentage with the U.S. Navy circumference method.
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Body Composition Calculator
Ideal Weight Calculator
Compare multiple legacy ideal-weight formulas and view a practical range instead of one fixed number.
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Body Composition Calculator
Lean Body Mass Calculator
Estimate lean body mass (fat-free mass) using Boer, James, and Hume formulas from height and weight.
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Planning Calculator
Body Recomposition Planner
Plan a realistic body-recomp timeline with body-fat targets, training frequency, calorie pacing, and protein guidance.
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Body Composition Calculator
FFMI Calculator
FFMI calculator: calculate your Fat-Free Mass Index to gauge muscularity relative to height and compare against natural training benchmarks.
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Body Composition Calculator
Waist-to-Hip Ratio Calculator
Calculate your waist-to-hip ratio and assess body composition using WHO guidelines.
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Guides & Content
Read the supporting guides, explainers, and benchmarks
This section groups the content cluster behind body composition, including topical articles plus tool-focused walkthroughs where they add useful context.
Guides
Body Composition 6 MIN READ
How to Calculate Your Ideal Weight
How to calculate your ideal weight using BMI, the Devine formula, body fat percentage, and waist-to-height ratio, plus why a healthy range beats one number.
Body Composition 6 MIN READ
How to Do a Body Recomposition
How to body recomp: build muscle and lose fat at the same time. Macro targets, training structure, recovery rules, and the realistic timeline expectations.
Body Composition 6 MIN READ
How to Measure Body Fat at Home: 4 Methods Compared
How to measure body fat at Home: 4 Methods Compared: compare the Navy tape method, smart scales, calipers, and visual estimation for home body fat measurement.
Body Composition 6 MIN READ
How to Track Body Fat Accurately
How to track body fat reliably. Standardize tape and caliper measurements, time them right, and turn the data into real body composition progress.
Glossary Terms
Body Composition 4 FAQS
What Is BMI? Simply Explained
Understand BMI (Body Mass Index): its definition, how it's calculated using height and weight, what your score means, and why it's a key health indicator.
Body Composition 4 FAQS
What Is Body Fat Percentage? Definition & How It's Measured
Learn what body fat percentage means, how it's calculated, the methods used to measure it (DEXA, BIA, calipers), and why it beats weight or BMI for health.
Body Composition 4 FAQS
What Is FFMI? Simply Explained
Learn what FFMI (Fat-Free Mass Index) is, how to calculate it, and why this metric is important for assessing muscularity relative to height and body fat.
Body Composition 4 FAQS
What Is Lean Body Mass? Simply Explained
Understand Lean Body Mass: its definition, why it matters for health and fitness, how to calculate it, and its impact on metabolism and body composition goals.
Comparisons
Body Composition 6 CRITERIA
BMI vs Body Fat Percentage
BMI vs body fat percentage: BMI is a weight-to-height ratio, body fat percentage measures adipose tissue directly. Pros, cons, and when each metric is most useful.
Body Composition 6 CRITERIA
Cutting vs Bulking: When to Do Each
Unravel the 'cutting' vs 'bulking' debate to plan body composition changes. Learn when to strategically focus on fat loss or muscle gain for peak fitness.
Body Composition 7 CRITERIA
How Accurate Is the Navy Body Fat Calculator vs Calipers
How accurate is the Navy body fat calculator? It reads within 3-4% of DEXA versus 2-3% for trained calipers. Navy wins on repeatability for solo tracking.
Formulas
Body Composition 3 VARIABLES
BMI Formula
BMI = weight in kilograms divided by height in meters squared. Quick screening number, blind to body composition. Cutoffs are 18.5 / 25 / 30 (WHO).
Body Composition 5 VARIABLES
Body Fat Percentage Formula (US Navy)
US Navy circumference-based body fat. Men: 86.010·log10(waist−neck) − 70.041·log10(height) + 36.76. Women: 163.205·log10(waist+hip−neck) − 97.684·log10(height) − 78.387.
Body Composition 4 VARIABLES
Body Recomposition Formula
Body recomposition formula: target_weight = LBM / (1 − target_BF%/100). weekly_fat_loss = (current_weight − target_weight) / weeks.
Fat Loss 3 VARIABLES
Calorie Deficit Formula
The calorie deficit formula: daily deficit = TDEE minus intake, with 1 lb fat about 3,500 cal and 1 kg about 7,700 cal, plus a worked weekly-loss example.
Body Composition 3 VARIABLES
FFMI Formula: Kouri-Adjusted Fat-Free Mass Index
FFMI formula: FFMI = LBM_kg / (height_m)² + 6.1·(1.8 − height_m). The +6.1·(1.8−h) normalizes to a 1.8 m reference. Natural ceiling ~25 male, ~22 female.
mobility 6 VARIABLES
Flexibility Score Formula
Flexibility score: Beighton hypermobility (0-9) + FMS Deep Squat (0-3). Beighton ≥5 suggests hypermobility; FMS ≤2 flags movement dysfunction.
Body Composition 2 VARIABLES
Ideal Weight Formula (Devine 1974)
Ideal weight formula from the Devine 1974 equation: men 50 + 2.3 kg per inch over 60, women 45.5 + 2.3, plus Robinson, Miller and Hamwi variants.
Fat Loss 4 VARIABLES
Katch-McArdle Formula
Katch-McArdle BMR = 370 + 21.6·LBM_kg. Uses lean body mass instead of total mass — more accurate when reliable body-fat data is available.
Body Composition 3 VARIABLES
Lean Body Mass Formula (Boer)
Lean body mass formula (Boer 1984). Male: LBM = 0.407·mass_kg + 0.267·height_cm − 19.2. Female: LBM = 0.252·mass_kg + 0.473·height_cm − 48.3.
Body Composition 5 VARIABLES
Max Muscular Potential Formula (Natural Ceiling)
Max muscular potential formula: natural FFMI ceiling near 25 for men and 21 for women (Kouri 1995), with monthly muscle gain rates by training age.
Nutrition Planning 3 VARIABLES
Protein Intake Formula
protein_g = mass_kg × goal_factor. Goal factors: 0.8 sedentary (RDA), 1.6 trained baseline, 1.8 deficit / hypertrophy, 2.2 advanced cut or older lifter.
Body Composition 3 VARIABLES
Waist-to-Hip Ratio Formula
Computes waist-to-hip ratio as waist circumference divided by hip circumference; WHO cardiometabolic risk cutoffs are 0.90 for men and 0.85 for women.
Examples
Body Composition 4 EXAMPLES
BMI Examples
Explore practical BMI examples across diverse scenarios, from athletes to seniors, revealing key insights into its utility and limitations for health.
Body Composition 4 EXAMPLES
Body Fat Examples
Explore diverse real-world body fat examples, from sedentary professionals to athletes and new mothers, revealing unique insights into health, performance.
Body Composition 4 EXAMPLES
Body Recomposition Examples
Explore real-world body recomposition examples, from busy professionals to athletes and new parents, revealing how to build muscle and lose fat.
Body Composition 4 EXAMPLES
FFMI Examples
Explore practical FFMI examples for athletes, beginners, and older adults. Learn how Fat-Free Mass Index reveals body composition and natural muscle limits.
Body Composition 4 EXAMPLES
Ideal Weight Examples
Discover diverse ideal weight examples for athletes, sedentary individuals, and more. Learn how factors like body composition, age, and lifestyle redefine.
Body Composition 4 EXAMPLES
Lean Body Mass Examples
Explore diverse lean body mass examples across fitness, health, and wellness scenarios. Understand its critical role in tracking real progress beyond just.