Updated Nutrition Planning Tool

Macronutrient Calculator

Convert calories into protein, carbs and fats, estimate your TDEE using Mifflin-St Jeor or Katch-McArdle BMR and build custom daily and per-meal macro plans for fat loss, maintenance or muscle gain.

Macro Split by Percentage Calories to Macros by Bodyweight TDEE & Goal-Based Macros Custom Per-Meal Macro Planner

Interactive Macronutrient Calculator Suite

Use the tabs to choose a simple macro split, convert calories and bodyweight into macros, calculate TDEE with goals using Mifflin-St Jeor or Katch-McArdle, and break your daily macros into per-meal targets.

This mode assumes protein, carbs and fats together make up 100% of your calorie intake. Protein and carbs are counted as 4 kcal per gram, fats as 9 kcal per gram.

Protein and fat are set by bodyweight; remaining calories are assigned to carbohydrates. This is a common approach for performance and physique goals.

You can choose between Mifflin-St Jeor (uses weight, height, age and gender) and Katch-McArdle (uses lean body mass from body fat %). Goal calories are applied to build your macro plan.

This mode divides your daily grams of protein, carbs and fats equally across your chosen number of meals. You can pair it with the other tabs to turn a daily macro target into practical meal goals.

Macronutrient Calculator – From Calories to Protein, Carbs and Fats

Macronutrients are the big three nutrients that provide energy: protein, carbohydrates and fats. This Macronutrient Calculator on MyTimeCalculator ties together the main formulas used in modern nutrition: calorie and macro conversions, basal metabolic rate (BMR), total daily energy expenditure (TDEE) and goal-based macro plans for fat loss, maintenance and muscle gain.

The core ideas are simple but powerful: calories come from macros, and your calorie needs come from your metabolism and activity. Once you connect these pieces with clear formulas, you can design a macro plan that fits your goals instead of guessing.

Calorie and Macronutrient Basics

Each gram of a macronutrient contributes a specific amount of energy:

  • Protein: 4 kilocalories per gram
  • Carbohydrates: 4 kilocalories per gram
  • Fats: 9 kilocalories per gram

If P, C and F denote daily grams of protein, carbs and fats, then total calories from macros are

Ctotal = 4P + 4C + 9F.

This calculator uses thatationship in both directions: it can start from calories and macro percentages to find grams, or start from grams per kilogram bodyweight and total calories to back out carbs.

Mode 1: Macro Split by Percentage

In the Macro Split tab you specify daily calories and choose what percentage of those calories come from protein, carbs and fats. If P%, C% and F% are those percentages and K is total calories, the formulas for macro grams are

  • Protein grams = (K × P% ÷ 100) ÷ 4
  • Carbohydrate grams = (K × C% ÷ 100) ÷ 4
  • Fat grams = (K × F% ÷ 100) ÷ 9

The percentages should add up to 100%. The calculator also reports how many calories are accounted for by your macro split so you can confirm the plan is internally consistent.

Mode 2: Calories and Bodyweight to Macros

Many evidence-based macro plans start from bodyweight rather than fixed percentages. In this mode you choose daily calories and set protein and fat in grams per kilogram of bodyweight. Let W be bodyweight in kilograms, p be target protein in grams per kilogram, f be target fat in grams per kilogram and K be daily calories. The equations are

  • Protein grams P = p × W
  • Fat grams F = f × W
  • Calories from protein = 4P
  • Calories from fat = 9F
  • Carbohydrate grams C = max{0, (K − 4P − 9F) ÷ 4}

Bodyweight can be entered in kilograms or pounds. When you choose pounds, the calculator first converts to kilograms using Wkg = Wlb × 0.453592. This gives you a macro plan that scales automatically with your size.

Mode 3: TDEE and Goal-Based Macros

Your Total Daily Energy Expenditure (TDEE) is the number of calories you burn per day including both rest and activity. The calculator first computes your basal metabolic rate (BMR) using one of two formulas, then scales it by an activity factor.

Mifflin-St Jeor Formula

Mifflin-St Jeor estimates BMR from weight, height, age and gender. Using weight W in kilograms, height H in centimeters and age A in years:

  • Men: BMR = 10W + 6.25H − 5A + 5
  • Women: BMR = 10W + 6.25H − 5A − 161

Katch-McArdle Formula

Katch-McArdle uses lean body mass (LBM). If body fat percentage is BF% then lean mass in kilograms is

LBM = W × (1 − BF% ÷ 100).

The Katch-McArdle BMR is

BMR = 370 + 21.6 × LBM.

This can be more accurate for lean or athletic individuals when body fat is known.

Activity Factor and TDEE

Once BMR is known, TDEE is modeled as

TDEE = BMR × ActivityFactor.

The activity factor depends on your typical daily movement and training:

  • Sedentary: 1.2
  • Lightly active: 1.375
  • Moderately active: 1.55
  • Very active: 1.725
  • Extra active: 1.9

Goal Calories

To set a goal, the calculator applies a simple multiplier to TDEE. If G is this multiplier, goal calories Kgoal are

Kgoal = TDEE × G.

Typical choices are

  • Fat loss: G ≈ 0.8 (about a 20% calorie deficit)
  • Maintenance: G = 1.0
  • Muscle gain: G ≈ 1.15 (about a 15% calorie surplus)

Macro Plan from TDEE

Once goal calories are set, the calculator applies bodyweight-based macro rules. If W is bodyweight in kilograms, recommended anchors often look like

  • Protein: P = 1.6–2.2 grams per kilogram (the calculator uses a default in this range)
  • Fats: F = 0.6–1.0 grams per kilogram (the calculator uses a mid-range value)
  • Carbs: C fills the remaining calories: C = [Kgoal − (4P + 9F)] ÷ 4

The TDEE tab combines BMR, activity level, goal multiplier and these macro formulas into a single workflow so you can go from basic body data to a complete macro plan.

Mode 4: Per-Meal Macro Planner

Daily targets only become practical when they are turned into meal-level decisions. In the Meal Planner tab you enter daily grams of protein, carbs and fats and choose a number of meals n. The calculator divides everything evenly:

  • Protein per meal = P ÷ n
  • Carbs per meal = C ÷ n
  • Fats per meal = F ÷ n
  • Calories per meal ≈ 4 × (P ÷ n) + 4 × (C ÷ n) + 9 × (F ÷ n)

You can use this to design balanced meals that hit your daily macro plan without constant mental math.

How to Choose Macro Ratios and Targets

There is no one universal best macro ratio, but some patterns are common:

  • Higher protein (for example 1.6–2.2 g/kg) supports muscle maintenance and growth, especially in a calorie deficit or during resistance training.
  • Moderate fats (for example 0.6–1.0 g/kg) help support hormones, joint health and absorption of fat-soluble vitamins.
  • Carbs adjust up or down based on training volume and calorie budget; they often take “what is left” after protein and fat are set.

The calculator lets you explore different scenarios: simple percentage splits for a quick plan, bodyweight-based settings for more precision and full TDEE-based planning when you want a structured approach around energy balance.

Using This Macronutrient Calculator Effectively

  • Start with the TDEE tab if you do not yet know your maintenance calories. Choose Mifflin-St Jeor by default or Katch-McArdle if you have a good body fat estimate and areatively lean.
  • Apply a moderate deficit for fat loss or surplus for muscle gain rather than extreme changes. The formulas assume sustainable adjustments, not crash diets.
  • Use the Calories and Bodyweight tab when you already have a calorie target but want to set protein and fat with grams per kilogram rules.
  • Refine the macro split in the percentage tab if you prefer to think in percentages or want to test different macro ratios at the same calorie level.
  • Finish with the Meal Planner tab to create consistent per-meal targets that match your daily macros.

This tool is intended for education and planning only. It does not replace medical advice, and it does not account for specific health conditions, medications or clinical nutrition needs. Always consult a qualified professional if you have medical concerns or highly specialized performance goals.

Macronutrient FAQs

Frequently Asked Questions Macros and Calories

Quick answers to help you interpret macro ratios, BMR, TDEE and goal-based nutrition plans.

No. Macros are targets, not perfection rules. Being roughly consistent over the week matters more than hitting exact numbers every single day. The calculator helps you set clear targets; small day-to-day variation is normal and expected.

For bodyweight change, total calories control the big picture. For performance, satiety and body composition, macro distribution matters a lot. The best approach is to set calories based on TDEE and goals, then allocate macros in a way that supports those goals and fits your preferences.

Very low protein intakes limit muscle growth, but beyond a certain point more protein does not add much benefit. Most research-based ranges for lifters and athletes fall between 1.6 and 2.2 grams of protein per kilogram of bodyweight per day, assuming adequate calories and training.

Yes. The calculator does not enforce a single macro style. You can set low-carb, high-carb, higher-fat or more balanced macro splits depending on what fits your training and preferences, as long as daily calories and protein are reasonable for your goals.

As your bodyweight, activity level or goals change, your TDEE and optimal macros also change. Many people adjust macros every few weeks based on progress, checking whether their actual weight trend matches what their calorie and macro plan predicts.

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