Calorie Calculator — Daily Calorie Needs (TDEE)
Calculate your daily calorie needs using the Mifflin-St Jeor equation. Get your BMR, TDEE, and calorie targets for weight loss, maintenance, and muscle gain — plus a full guide on macros, safe deficit sizes, and why activity level matters.
Your Daily Calorie Targets
Understanding Your Calorie Needs: BMR and TDEE
Your body burns calories constantly — even at complete rest. The number of calories your body needs just to sustain basic functions (breathing, circulation, cell repair) is called your Basal Metabolic Rate (BMR). Add the calories burned through daily movement and exercise, and you get your TDEE (Total Daily Energy Expenditure) — the number of calories you need to maintain your current weight.
The Mifflin-St Jeor Equation
This calculator uses the Mifflin-St Jeor equation, which research consistently shows to be the most accurate BMR formula for most adults:
Females: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
TDEE = BMR × Activity Multiplier. For a 30-year-old male, 70 kg, 175 cm, moderately active: BMR = (700 + 1,093.75 − 150 + 5) = 1,649 cal/day. TDEE = 1,649 × 1.55 = 2,556 cal/day.
Activity Multipliers Explained
Choosing the right activity level is the most common source of error. Be honest — most office workers are Sedentary or Lightly Active, even if they exercise 3 days a week.
| Level | Multiplier | Who It Fits |
|---|---|---|
| Sedentary | 1.2× | Desk job, no structured exercise, daily steps <5,000 |
| Lightly Active | 1.375× | Light walks or gym 1–3 days/week, mostly sitting job |
| Moderately Active | 1.55× | Exercise 3–5 days/week with moderate intensity |
| Very Active | 1.725× | Hard cardio or weight training 6–7 days/week |
| Extremely Active | 1.9× | Twice-a-day training or hard physical labor + exercise |
If you're not losing weight despite being in a "deficit," the most likely culprit is overestimating your activity level. Try dropping one level and reassessing after 2–3 weeks.
Calorie Targets for Different Goals
Weight loss: A deficit of 500 calories/day produces approximately 0.45 kg (1 lb) of fat loss per week. A 750 cal/day deficit yields ~1.5 lb/week, which is generally the upper limit of sustainable fat loss without significant muscle loss. Going below 1,200 cal/day (women) or 1,500 cal/day (men) is not recommended without medical supervision, as it risks nutrient deficiencies and metabolic adaptation.
Muscle gain (lean bulk): A surplus of 200–400 cal/day supports muscle growth while minimizing fat gain. Larger surpluses build muscle faster in theory but also increase fat storage. Beginners often make good gains at maintenance calories with sufficient protein and progressive resistance training.
Maintenance: Eating at TDEE maintains current weight. Weigh yourself weekly (same conditions each time) and if weight trends up or down over 3–4 weeks, adjust by 100–150 calories and re-evaluate.
Protein, Carbs, and Fats: How to Split Your Calories
Once you have your calorie target, consider how to distribute it across macronutrients:
- Protein: 1.6–2.2g per kg of body weight for muscle preservation or growth. At 70 kg, target 112–154g/day. Protein has 4 cal/gram.
- Fat: A minimum of 0.5–1g per kg body weight is essential for hormonal health. Fat has 9 cal/gram.
- Carbohydrates: Fill in remaining calories. Carbs have 4 cal/gram and fuel training performance.
A common general-purpose split is 30% protein / 35% carbs / 35% fat, though this varies by preference and activity type.
Why Your Results May Vary
The Mifflin-St Jeor equation is accurate to within ±10% for most people. Individual metabolism varies due to genetics, hormonal factors, gut microbiome, and history of calorie restriction. Treat this number as a starting estimate and adjust based on real-world weight trends over 3–4 weeks.
Frequently Asked Questions
Studies consistently show the Mifflin-St Jeor equation is accurate to within roughly 10% for most non-obese adults. It tends to overestimate slightly for very obese individuals and underestimate for very muscular individuals (since muscle burns more calories than fat at rest). Use it as a starting point and adjust based on 3–4 weeks of real-world data.
TDEE (Total Daily Energy Expenditure) is the total number of calories you burn in a day, accounting for both your resting metabolism and all physical activity. It is the number that determines whether you gain, lose, or maintain weight. Eating above TDEE leads to weight gain; eating below leads to weight loss.
Not with this calculator. The activity multiplier already accounts for your exercise when estimating TDEE. If you selected the correct activity level, your exercise is included. Only eat back calories if you have an unexpectedly hard workout day that is well above your typical routine.
A deficit of 500 calories per day (producing ~1 lb/week weight loss) is generally considered safe and sustainable for most adults. Losing faster than 1–1.5 lbs per week risks muscle loss, nutrient deficiencies, and metabolic slowdown. Never go below 1,200 calories/day (women) or 1,500 calories/day (men) without medical supervision.
For general health: 0.8g per kg of body weight (the RDA). For preserving or building muscle while in a calorie deficit: 1.6–2.2g per kg. At 70 kg, that's 112–154g/day. Higher protein intakes help maintain muscle during weight loss and increase satiety, making the deficit easier to sustain.
Common reasons: (1) overestimating your activity level — most people are Sedentary or Lightly Active; (2) underestimating portion sizes — even small systematic errors add up; (3) water retention masking fat loss, especially around menstruation or after high-sodium meals; (4) metabolic adaptation after prolonged restriction. Track accurately for 3–4 weeks before adjusting.
Yes, but with reduced accuracy. As people age, muscle mass declines (sarcopenia), which lowers BMR. The Mifflin-St Jeor equation does account for age, but older adults often have meaningfully lower metabolisms than the formula predicts. If you are over 60 and find the numbers do not match your experience, try reducing the estimate by 5–10%.
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