Calorie Calculator (TDEE) and Macro Calculator
Your daily calorie need (TDEE) is your resting metabolism (BMR) multiplied by an activity factor. The BuyTheWhey calorie calculator uses the Mifflin-St Jeor equation, then sets a target for fat loss (−20%), maintenance or muscle gain (+10%) and splits it into protein, carbs and fat.
Calorie & Macro Calculator
BMR, TDEE and daily protein/carbs/fat for your goal.
Estimates for healthy adults, for general information only — not medical advice.
The formula
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5.
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161.
- TDEE = BMR × 1.2 (sedentary) to 1.9 (athlete).
- Macros: protein 1.8 g/kg (2.0 g/kg when losing fat), fat 25% of calories, carbohydrates the rest.
Frequently asked questions
How many calories should I eat to lose fat?
A deficit of about 20% below your TDEE is a common, sustainable starting point — usually 0.5–1% of body weight lost per week. Adjust after 2–3 weeks based on your actual weight trend.
Which BMR formula is most accurate?
Mifflin-St Jeor (1990) is the equation most often recommended for healthy adults because it predicted measured resting metabolic rate more closely than older equations such as Harris-Benedict.
How many calories do I need to build muscle?
A small surplus of about 5–10% above TDEE, combined with strength training and 1.6–2.2 g/kg of protein, supports muscle gain while limiting fat gain.
Sources
- Mifflin et al., American Journal of Clinical Nutrition, 1990
- ISSN Position Stand: Protein and Exercise (Jäger et al., 2017)
These calculators give estimates for healthy adults and are for general information only. Speak to a doctor or registered dietitian before major diet changes.