THE BODY NUMERAL GUIDES
Understand the number.
Know its limits.
Practical notes on taking measurements, comparing estimates, and understanding what a result can tell you.
FEATURED · Methods & limits
Why calculators give different answers
Understand the methods behind the numbers.
By Body Numeral editorial team · 7 min read
Read the guideAll guides by topic
24 GUIDES · NEWEST FIRSTBody composition
Are smart scales accurate for body fat?
Learn what a smart scale measures, why body-fat estimates differ, and how to check a change with a worked example.
By Body Numeral editorial team · 10 min read ·
What is ABSI? How to read A Body Shape Index result
Learn how ABSI uses waist, height, and weight. Follow a worked example and read the age and sex reference score without treating it as a diagnosis.
By Body Numeral editorial team · 9 min read ·
What does an ideal body weight calculator actually mean?
Compare four ideal body weight formulas with a worked example. See why their results differ and why no single number is a personal target.
By Body Numeral editorial team · 10 min read ·
What is body roundness index? How to read a BRI result
See how body roundness index uses waist and height, check a worked example, and learn what the result can and cannot show.
By Body Numeral editorial team · 10 min read ·
BMI vs body fat percentage: what is the difference?
Compare a weight-to-height screening measure with an estimate of the share of body weight that is fat.
By Body Numeral editorial team · 7 min read ·
Body Fat Percentage vs Fat Mass: The Difference
See how a percentage becomes an estimated mass and why the method stays part of the result.
By Body Numeral editorial team · 13 min read ·
Waist-to-Height Ratio vs BMI: What Each Number Shows
Compare the inputs, uses, and limits of two common screening numbers.
By Body Numeral editorial team · 8 min read ·
What FFMI measures and what it cannot tell you
See how fat-free mass index uses an estimated body-fat input and height, and why it is different from muscle mass or a personal limit.
By Body Numeral editorial team · 13 min read ·
How muscle mass is estimated
See what a waist-based muscle estimate uses and why it is different from lean mass.
By Body Numeral editorial team · 8 min read ·Measurement
How to convert pounds, feet, and inches for body calculators
Convert height, weight, and tape readings with the right units. Follow a worked example and avoid rounding or mixing measurement sites.
By Body Numeral editorial team · 9 min read ·
How to calculate BMI: metric and pounds-and-inches examples
Calculate body mass index from weight and height, check the units and rounding, and use the right age reference.
By Body Numeral editorial team · 11 min read ·
How to calculate waist-to-hip ratio
Divide a waist measurement by a hip measurement with matching units, then record the method and rounding.
By Body Numeral editorial team · 9 min read ·
Waist circumference vs waist-to-height ratio
Compare a waist measurement in centimetres or inches with the same measurement divided by height.
By Body Numeral editorial team · 14 min read ·
How to take tape measurements
Use the right landmarks for your selected method.
By Body Numeral editorial team · 7 min read ·Energy & nutrition
Gross vs net exercise calories: include or subtract rest
Compare session calories with and without resting energy. Work through a gross-to-net example and keep time, units, and the resting baseline consistent.
By Body Numeral editorial team · 8 min read ·
How to convert macro percentages into grams
Convert a calorie amount and a stated carbohydrate, protein, and fat split into grams.
By Body Numeral editorial team · 8 min read ·
Kilojoules to Calories (kJ to kcal): converter and table
Convert kJ to Calories or Calories to kJ with one factor, 4.184. Use the live converter or the table of common food-label values.
By Body Numeral editorial team · 10 min read ·
Protein calculator results: what the reference value means
Understand what a grams-per-kilogram reference converts and what it cannot tell you.
By Body Numeral editorial team · 9 min read ·
BMR vs RMR vs TDEE: What Each Number Means
Compare resting and whole-day energy numbers without treating an estimate as a measurement.
By Body Numeral editorial team · 13 min read ·
How to choose an activity level
Include your whole day, not only your workouts.
By Body Numeral editorial team · 7 min read ·Fitness
VO₂ max units: convert L/min and mL/kg/min
Convert oxygen uptake between L/min and mL/kg/min with worked examples. Use the weight from the same test and keep estimates separate from measurements.
By Body Numeral editorial team · 7 min read ·
How to calculate a one-rep max estimate
Calculate a one-rep max estimate from a completed set, compare three equations, and understand what the result can and cannot tell you.
By Body Numeral editorial team · 10 min read ·Methods & tracking
Clear about the process.
Each guide links to sources and separates method limits from personal advice.