Lean Mass Macro Calculator

Calculator Inputs

Unit System

Body Weight

Enter current body weight in kilograms or pounds.

Body Fat %

Lean mass is derived from weight and body fat.

Activity Factor

Goal

Custom Calorie Adjustment %

Use negative values for cutting and positive values for bulking.

BMR Formula

Protein Target

Custom Protein g/kg Lean Mass

Useful for highly specific coaching or dieting rules.

Fat Target

Custom Fat g/kg Lean Mass

Fat is set first, then carbohydrates use the remaining calories.

Meals Per Day

The meal table divides macros evenly across meals.

Example Data Table

This example shows how one set of inputs can translate into lean mass, calories, and daily macro targets.

Weight	Body Fat	Lean Mass	Goal	Target Calories	Protein	Carbs	Fat
75 kg	18%	61.5 kg	Maintain	2,350 kcal	135 g	249 g	49 g
82 kg	14%	70.5 kg	Lean Bulk	2,980 kcal	155 g	364 g	56 g
68 kg	26%	50.3 kg	Cut	1,710 kcal	111 g	156 g	40 g

Formula Used

Lean Mass = Body Weight × (1 − Body Fat ÷ 100)

Katch-McArdle BMR = 370 + (21.6 × Lean Mass in kg)

Cunningham BMR = 500 + (22 × Lean Mass in kg)

TDEE = BMR × Activity Factor

Target Calories = TDEE × (1 + Goal Adjustment %)

Protein = Lean Mass × Protein Multiplier

Fat = Lean Mass × Fat Multiplier

Carbohydrates = (Target Calories − Protein Calories − Fat Calories) ÷ 4

Protein and carbohydrates provide four calories per gram. Fat provides nine. The calculator sets protein and fat first, then assigns the remaining calories to carbohydrates.

How to Use This Calculator

Choose metric or imperial units.
Enter body weight and estimated body fat percentage.
Select an activity factor that matches your weekly movement and training load.
Choose your goal, such as cutting, maintaining, or bulking.
Pick a BMR formula and protein or fat profiles, or enter custom multipliers.
Set meals per day, then submit the form.
Review the summary, macro table, meal split table, and charts.
Download the results as CSV or PDF for meal planning or coaching records.

Frequently Asked Questions

1. What is lean mass?

Lean mass is body weight minus stored body fat. It includes muscle, organs, bones, water, and other non-fat tissues used in lean-mass-based calorie equations.

2. Why use lean mass instead of total weight?

Lean mass often gives a more personalized baseline for calorie and macro planning, especially when body fat varies widely between people with the same body weight.

3. Which BMR formula should I choose?

Katch-McArdle is popular for body-composition-based planning. Cunningham is another lean-mass formula and may suit performance-focused users. Comparing both can help you choose a practical starting point.

4. How much protein should I set?

Higher protein targets are commonly used during cutting or intense training. Moderate settings may suit maintenance phases. The custom option helps align the plan with coaching preferences.

5. Why did carbohydrates drop to zero?

This happens when target calories are too low for the chosen protein and fat floors. The calculator automatically raises calories to preserve those minimum macro targets.

6. Are meal splits automatically timed around workouts?

No. The meal table divides totals evenly. You can still move more carbohydrates toward pre-workout or post-workout meals if your training schedule benefits from it.

7. Is this calculator suitable for medical nutrition therapy?

No. It is a planning tool for general fitness nutrition. Medical conditions, pregnancy, eating disorders, or therapeutic diets require qualified professional guidance.

8. How often should I recalculate?

Recalculate after meaningful changes in body weight, body fat, activity, or goal phase. Many people review targets every two to four weeks.