Calorie & Macro Calculator

Know Exactly What to Eat for Your Goals

Whether you are trying to lose body fat, build muscle, or simply maintain your current weight, knowing your daily calorie needs is the foundation of any effective nutrition plan. This calculator uses the Mifflin-St Jeor equation — widely regarded as the most reliable BMR formula for healthy adults — to estimate how many calories your body burns each day.

How the Mifflin-St Jeor Formula Works

Published in 1990, the Mifflin-St Jeor equation calculates your Basal Metabolic Rate (BMR) using four variables: weight, height, age, and gender.

For men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) + 5

For women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) - 161

Your BMR represents the calories your body needs at complete rest. To get your Total Daily Energy Expenditure (TDEE), the calculator multiplies your BMR by an activity factor ranging from 1.2 for sedentary lifestyles to 1.9 for extremely active individuals.

Understanding Your Calorie Target

Your TDEE is your maintenance level — the number of calories at which your weight stays roughly the same. To change your weight:

Goal	Adjustment	Expected Rate
Mild weight loss	-250 cal/day	~0.25 kg (0.5 lb) per week
Moderate weight loss	-500 cal/day	~0.5 kg (1 lb) per week
Aggressive weight loss	-750 cal/day	~0.75 kg (1.5 lbs) per week
Mild weight gain	+250 cal/day	~0.25 kg (0.5 lb) per week
Moderate weight gain	+500 cal/day	~0.5 kg (1 lb) per week
Aggressive weight gain	+750 cal/day	~0.75 kg (1.5 lbs) per week

These projections assume a consistent calorie intake. Real-world results depend on many factors including sleep, stress, hormonal fluctuations, and adherence.

Why Macronutrients Matter

Calories tell you how much to eat. Macronutrients — protein, carbohydrates, and fat — tell you what to eat. Each macro serves a different function:

Protein (4 cal/g) is essential for muscle repair and growth, immune function, and satiety. Most nutrition guidelines recommend 1.6 to 2.2 grams per kilogram of body weight for active individuals.

Carbohydrates (4 cal/g) are your body’s preferred energy source, especially for high-intensity exercise. They fuel your brain, muscles, and central nervous system.

Fat (9 cal/g) supports hormone production, nutrient absorption, and cell membrane health. Dietary fat is calorie-dense, so portions matter even though fat is not inherently unhealthy.

The default 30/40/30 split (protein/carbs/fat) works well as a balanced starting point. Athletes may prefer higher carbs, while those focused on satiety may increase protein. Use the sliders to customize the ratio for your needs.

Tips for Accuracy

Calorie calculators are estimates, not exact prescriptions. To get the most useful results:

• Weigh yourself consistently (same time of day, same conditions) and track weekly averages rather than daily fluctuations.
• Be honest about your activity level. Most people overestimate how active they are.
• Adjust based on real-world results after two to three weeks. If your weight is not changing as expected, adjust calories by 100 to 200 per day.
• Consider food tracking for at least a few weeks to calibrate your intuition about portion sizes.

This tool gives you a solid starting point. Your body provides the feedback to fine-tune it.