Macronutrient Calculator
Calculate your ideal daily intake of protein, carbs, and fat based on your body, activity level, and fitness goal. All calculations run locally in your browser.
What Are Macronutrients?
Macronutrients are the three main nutrients your body needs in large amounts to function: protein, carbohydrates, and fat. Each plays a distinct role in your health and performance.
- Protein (4 calories per gram) builds and repairs muscle tissue, supports immune function, and helps you feel full. Found in meat, fish, eggs, dairy, legumes, and tofu.
- Carbohydrates (4 calories per gram) are your body's preferred energy source, fueling your brain and muscles. Found in grains, fruits, vegetables, and legumes.
- Fat (9 calories per gram) supports hormone production, nutrient absorption, and cell membrane health. Found in oils, nuts, seeds, avocado, and fatty fish.
Unlike micronutrients (vitamins and minerals), macronutrients provide the energy your body uses throughout the day. The balance between these three macros affects your body composition, energy levels, and overall health.
How to Calculate Your Macros
Calculating your macros involves two steps:
- Step 1: Find your TDEE. Your Total Daily Energy Expenditure is the number of calories you burn in a day, including your basal metabolic rate (BMR) and physical activity. This calculator uses the Mifflin-St Jeor equation, which is considered the most accurate BMR formula for most adults.
- Step 2: Apply a macro ratio. Based on your goal (fat loss, maintenance, or muscle gain), your total calories are divided into percentages for protein, carbs, and fat. The grams for each macro are then calculated using their calorie density: 4 cal/g for protein and carbs, 9 cal/g for fat.
For fat loss, the calculator applies a 500-calorie deficit (about 0.45 kg or 1 lb of fat loss per week). For muscle gain, it adds a 300-calorie surplus to support growth while limiting excess fat gain.
Macro Ratios by Goal
| Goal | Protein | Carbs | Fat | Calorie Adjustment |
|---|---|---|---|---|
| Lose Weight | 40% | 30% | 30% | -500 kcal |
| Maintain Weight | 30% | 40% | 30% | None |
| Build Muscle | 30% | 45% | 25% | +300 kcal |
These ratios are general guidelines based on sports nutrition research. Individual needs may vary depending on training intensity, body composition, metabolic health, and personal preferences. Consider consulting a registered dietitian for a personalized plan.
Why Protein Matters for Weight Loss
The higher protein ratio (40%) during fat loss serves multiple purposes. Protein has the highest thermic effect of food, meaning your body burns more calories digesting it. It also preserves lean muscle mass during a calorie deficit and promotes satiety, helping you stick to your plan.
Adjusting Macros Over Time
Your macro needs are not static. As your weight changes, your TDEE changes too. Recalculate your macros every 4-6 weeks or whenever your weight shifts by more than 2-3 kg (5-7 lbs). If you plateau, a small adjustment to your calorie target or macro split can help you break through.
Track Your Blood Work with Health3
Nutrition is one piece of the puzzle. Track your blood work and biomarkers over time to see how your body is really doing with Health3.
