What is body recomposition?

Recomposition means losing fat and gaining muscle over the same period. Weight may fall, stay similar or rise, depending on the balance of those changes. Track waist, body measurements and training performance alongside the weight trend; none is conclusive on its own.

Which calculator first?

Body fat percentage. From there, lean body mass is one subtraction and adds a Katch-McArdle comparison; BMR comes from Mifflin-St Jeor, TDEE scales off BMR, macros split out of TDEE. Waist-hip and waist-height sit alongside as monthly risk checks.

How accurate are the formulas?

Each calculator uses published, peer-reviewed equations: Mifflin-St Jeor for BMR, with Katch-McArdle as a lean-mass comparison, US Navy or skinfold for body fat, WHO and ACSM thresholds for risk. Point estimates inside a band, useful for direction.

Both. Kilograms and centimeters or pounds and inches. The formulas convert internally, the output is the same number.

How do these relate to the Recomp AI app?

The app runs the same formulas, attached to daily food logs, weigh-ins, and a body fat trend. The calculators here return a point estimate. The app returns the same numbers tracked over time.

/ tools

Body recomposition calculators.

Pick the number you need now: BMI, body fat, lean mass, BMR, TDEE, macros, protein, water, waist ratios, or weight loss pace.

Calculators: 12
Categories: 03

/ index

Eleven calculators.

Each takes the inputs you can measure with a scale and a tape, runs one formula, returns one number. Grouped by what the number describes.

Composition

01 / composition

Body fat percentage, lean body mass, BMI. What the bodyweight is made of.

01BMI CalculatorHeight and weight, one division, the WHO band you fall in.kg/m² · band
02Body Fat CalculatorBody fat percentage from skinfolds or US Navy tape, with the published mortality evidence for context.% · band
03Lean Body MassEverything that is not fat. The base muscle, bone, water, and organs sit on.kg / lb

Energy

02 / energy

BMR, TDEE, macros, protein, water, and the recomposition target. Calories in, calories out, and what they are made of.

Ratios and pace

03 / ratios and pace

Waist over hip. Waist over height. Weeks to a weight loss target.

/ how they connect

Eleven calculators, one set of inputs.

Composition and progress signals

Body-fat estimates, lean-mass estimates, waist measurements and training performance add context. Compare them over time using consistent methods. Their pattern is more useful than any single reading.

Weight and energy estimates

BMI and weight describe size; BMR and TDEE estimate energy needs. Any can change during recomposition. None separates fat loss from muscle gain.

Why they share a page

Each calculator runs on the same inputs: height, weight, age, sex, activity, sometimes a tape measurement. Calculate body fat and lean body mass is one subtraction away. Lean mass adds a BMR comparison and scales protein, BMR scales to TDEE, TDEE splits into macros. Eleven outputs from one set of measurements.

/ faq

Common questions

What is body recomposition?: Recomposition means losing fat and gaining muscle over the same period. Weight may fall, stay similar or rise, depending on the balance of those changes. Track waist, body measurements and training performance alongside the weight trend; none is conclusive on its own.
Which calculator first?: Body fat percentage. From there, lean body mass is one subtraction and adds a Katch-McArdle comparison; BMR comes from Mifflin-St Jeor, TDEE scales off BMR, macros split out of TDEE. Waist-hip and waist-height sit alongside as monthly risk checks.
How accurate are the formulas?: Each calculator uses published, peer-reviewed equations: Mifflin-St Jeor for BMR, with Katch-McArdle as a lean-mass comparison, US Navy or skinfold for body fat, WHO and ACSM thresholds for risk. Point estimates inside a band, useful for direction.
Metric or imperial?: Both. Kilograms and centimeters or pounds and inches. The formulas convert internally, the output is the same number.
How do these relate to the Recomp AI app?: The app runs the same formulas, attached to daily food logs, weigh-ins, and a body fat trend. The calculators here return a point estimate. The app returns the same numbers tracked over time.