Whether you're training for a marathon, lifting in the gym, or just trying to stay active, what you eat directly fuels your performance and recovery. The Sports Nutrition Calculator helps you estimate your daily calorie needs and macronutrient targets (protein, carbohydrates, and fat) based on your body weight, activity level, and fitness goal.
Simply enter your weight, choose your activity level and goal (lose fat, maintain, or build muscle), and the calculator will provide personalized daily targets. You'll also get a per-meal breakdown and a simple hydration guideline to keep you performing at your best. This tool is ideal for athletes, fitness enthusiasts, and anyone looking to optimize their nutrition for better results.
⚙️ Your Daily Nutrition Targets
How to Use This Tool
Enter your current body weight and select the unit (kg or lb). Choose the activity level that best matches your typical weekly training, then pick your primary goal: lose fat, maintain weight, or build muscle. Click Calculate to see your estimated daily calorie target, macronutrient breakdown (protein, carbs, fat), and a hydration recommendation. Use the quick-fill buttons to load common example weights, or reset to start over.
The calculator uses the Mifflin-St Jeor equation to estimate your basal metabolic rate (BMR), then multiplies by an activity factor to get your total daily energy expenditure (TDEE). It then applies a calorie adjustment based on your goal: a deficit for fat loss, a surplus for muscle gain, or no change for maintenance. Protein and fat targets are set per kilogram of body weight, and the remaining calories are allocated to carbohydrates.
Formula Explained
The Mifflin-St Jeor equation is a widely used formula for estimating resting metabolic rate:
BMR (men) = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
BMR (women) = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
This calculator uses a default height of 175 cm and age of 30 for simplicity, which is fine for most users. For more precision, you can adjust these values manually in the formula. TDEE is then BMR × activity factor, where activity factors range from 1.2 (sedentary) to 1.9 (very active).
Macronutrient targets are based on sports nutrition guidelines: protein at 1.6–2.2 g/kg for athletes, fat at 0.8–1.0 g/kg, and the remainder from carbohydrates. These ranges support muscle repair, hormone function, and training performance.
Worked Examples
Example 1: A 70 kg male, moderately active (1.55), wants to maintain weight. BMR = 10×70 + 6.25×175 − 5×30 + 5 = 700 + 1093.75 − 150 + 5 = 1648.75 kcal. TDEE = 1648.75 × 1.55 ≈ 2556 kcal. Protein = 70 × 1.8 = 126 g, Fat = 70 × 0.8 = 56 g, Carbs = (2556 − 126×4 − 56×9) / 4 = (2556 − 504 − 504) / 4 = 1548 / 4 = 387 g.
Example 2: A 60 kg female, very active (1.725), wants to lose fat. BMR = 10×60 + 6.25×175 − 5×30 − 161 = 600 + 1093.75 − 150 − 161 = 1382.75 kcal. TDEE = 1382.75 × 1.725 ≈ 2385 kcal. With a 500 kcal deficit, target = 1885 kcal. Protein = 60 × 1.8 = 108 g, Fat = 60 × 0.8 = 48 g, Carbs = (1885 − 432 − 432) / 4 = 1021 / 4 ≈ 255 g.
Tips & Best Practices
- Adjust your calorie target gradually — a 300–500 kcal deficit or surplus is a safe starting point.
- Prioritize protein at each meal to support muscle maintenance and satiety.
- Time carbohydrates around workouts for better performance and recovery.
- Stay hydrated: aim for ~33 ml per kg of body weight, more if you sweat heavily.
- Reassess your numbers every 4–6 weeks as your weight and activity change.
Factors Affecting Accuracy
This calculator provides estimates, not medical advice. Individual metabolic rates vary due to genetics, muscle mass, and hormonal factors. The default height and age may not match your profile, so results can differ from your actual needs. For precise guidance, consider consulting a registered dietitian or sports nutritionist.
Frequently Asked Questions
How many calories should I eat to build muscle?
Typically a surplus of 200–300 kcal above maintenance, combined with progressive resistance training, supports lean muscle gain without excessive fat storage.
Is it okay to eat carbs at night?
Yes — total daily carbohydrate intake matters more than timing. Eating carbs after evening workouts can aid recovery and sleep.
Do I need protein supplements?
Not necessarily. Whole foods like chicken, fish, eggs, dairy, and legumes can meet your protein needs. Supplements are convenient but not essential.
How often should I recalculate?
Every 4–6 weeks or after a significant weight change (5% or more) to keep your targets aligned with your current body composition.
Additional Resources
For more detailed sports nutrition guidance, visit the Academy of Nutrition and Dietetics or the National Strength and Conditioning Association. You can also explore our protein calculator for men or calories burned during aerobics for more specific estimates.