Macro & TDEE Calculator: Mifflin-St Jeor Equation
Calculate your Total Daily Energy Expenditure (TDEE) and optimal protein, carb, and fat macro targets for cutting, maintenance, or muscle building.
TL;DR: To build muscle or lose fat predictably, you must manage energy balance (calories) and macronutrient distribution (protein, carbs, and fats). The Mifflin-St Jeor equation provides the most scientifically reliable baseline for calculating your Total Daily Energy Expenditure (TDEE).
Whether your goal is a lean calorie deficit, maintenance recomposition, or a clean muscle-building surplus, dialing in your daily macronutrient split provides the physiological fuel your body needs to recover and adapt.
Use the interactive calculator below to determine your precise daily calorie and macronutrient targets.
Interactive Macro & TDEE Calculator
BMR & TDEE Science Explained
To understand where your macro numbers come from, it helps to understand the energy balance hierarchy:
| Energy Metric | Definition | Primary Determining Factors |
|---|---|---|
| BMR (Basal Metabolic Rate) | Minimum calories needed to keep your body alive at rest. | Age, gender, height, body mass, lean muscle ratio. |
| NEAT (Non-Exercise Activity) | Calories burned through daily movement (walking, standing). | Daily step count, occupation, active lifestyle. |
| TEF (Thermic Effect of Food) | Energy used to digest and process macronutrients. | High for protein (~20–30%), low for fats (~0–3%). |
| EAT (Exercise Activity) | Calories burned during deliberate workouts. | Gym session duration, training intensity, heart rate. |
Macronutrient Distribution Hierarchy
Once daily total calories are set based on your goal, allocate your macronutrients according to these evidence-based ratios:
- Protein (Highest Priority): Set at 1.6 to 2.2 grams per kg of body weight (0.8–1.0g per lb). Protein fuels muscle protein synthesis (MPS) and preserves lean tissue during a calorie cut.
- Fats (Hormonal Baseline): Set at 20% to 30% of total daily calories. Adequate dietary fat is required for testosterone production and cell membrane integrity.
- Carbohydrates (Performance Engine): Allocate all remaining calories to carbs. Carbohydrates store as muscle glycogen, providing the primary ATP energy source for heavy compound lifting.
Fuel Your Training, Log Your Performance
Nutrition provides the building blocks, but progressive overload in the gym provides the stimulus. No macro split will build muscle if your training volume remains stagnant week after week.
Keep your gym tracking as streamlined as your nutrition planning. With Beau, you log workouts in seconds by speaking or typing naturally:
“Squat 275 lbs 4x6, bench press 205 lbs 3x8”
Beau turns natural-language text into structured sets, reps, and volume analytics on iPhone.
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