Calorie Calculator
Calculate your daily caloric needs using the Mifflin-St Jeor equation. Get personalized targets for weight maintenance, loss, or gain with macronutrient breakdown.
Daily Calories to Maintain Weight
2,633
cal/day · BMR: 1,699 · Activity: Moderately Active
Weight Loss
Maintain Weight
2,633
calories/day
Weight Gain
Suggested Daily Macros (at maintenance)
197g
Protein (30%)
263g
Carbs (40%)
88g
Fat (30%)
These are estimates based on the Mifflin-St Jeor equation. Individual metabolism varies by genetics, hormones, and body composition. Never go below 1,200 cal/day (women) or 1,500 cal/day (men) without medical supervision. Consult a dietitian for personalized plans.
How the Calorie Calculator Works
This calculator uses a two-step process: first it estimates your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, then multiplies by an activity factor to determine your Total Daily Energy Expenditure (TDEE).
Mifflin-St Jeor Equation
Male: BMR = (10 × weightkg) + (6.25 × heightcm) − (5 × age) + 5
Female: BMR = (10 × weightkg) + (6.25 × heightcm) − (5 × age) − 161
TDEE = BMR × Activity Multiplier
Activity Multipliers
| Level | Multiplier | Description |
|---|---|---|
| Sedentary | ×1.2 | Desk job, little exercise |
| Lightly Active | ×1.375 | Light exercise 1-3 days/wk |
| Moderately Active | ×1.55 | Moderate exercise 3-5 days/wk |
| Very Active | ×1.725 | Hard exercise 6-7 days/wk |
| Extra Active | ×1.9 | Athlete, physical job + training |
Example Calculation
30-year-old male, 175 cm, 75 kg, moderately active:
- • BMR = (10 × 75) + (6.25 × 175) − (5 × 30) + 5 = 1,694 cal/day
- • TDEE = 1,694 × 1.55 = 2,625 cal/day
- • Weight loss (−500): 2,125 cal/day → ~0.5 kg/week
- • Weight gain (+500): 3,125 cal/day → ~0.5 kg/week
Calorie Deficit Guidelines
- 250 cal deficit: ~0.25 kg/week — very sustainable, minimal hunger
- 500 cal deficit: ~0.5 kg/week — standard recommendation, sustainable
- 1000 cal deficit: ~1 kg/week — aggressive, may lose muscle without adequate protein
- Safety floor: Never below 1,500 (men) / 1,200 (women) without medical supervision
Why Mifflin-St Jeor Over Harris-Benedict?
The Harris-Benedict equation (1919, revised 1984) tends to overestimate caloric needs by 5-15%, particularly in overweight individuals. The Mifflin-St Jeor equation (1990) was validated against indirect calorimetry and is recommended by the Academy of Nutrition and Dietetics as the most reliable predictive equation for healthy adults.
Frequently Asked Questions
What is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation (1990) is currently considered the most accurate formula for estimating Basal Metabolic Rate (BMR) in healthy adults. For males: BMR = (10 × weight_kg) + (6.25 × height_cm) - (5 × age) + 5. For females: BMR = (10 × weight_kg) + (6.25 × height_cm) - (5 × age) - 161. It was validated against indirect calorimetry and performs better than the older Harris-Benedict equation.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just to keep your heart beating, lungs breathing, and cells functioning. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor, representing total calories burned including all physical activity. TDEE is what you should base your diet on.
How many calories should I eat to lose weight?
A safe rate of weight loss is 0.5-1 kg (1-2 lbs) per week, requiring a daily deficit of 500-1000 calories below your TDEE. Never go below 1,500 cal/day (men) or 1,200 cal/day (women) without medical supervision. A 500 cal/day deficit is sustainable for most people and results in approximately 0.5 kg of fat loss per week.
How accurate is this calculator?
The Mifflin-St Jeor equation estimates BMR within ±10% for most people. The biggest source of error is the activity multiplier, which is a rough estimate. For precise numbers, track your actual calorie intake and weight changes over 2-3 weeks, then adjust. Indirect calorimetry at a clinic provides the most accurate BMR measurement.
Does muscle mass affect calorie needs?
Yes. Muscle tissue burns more calories at rest than fat tissue (~6 cal/lb/day vs ~2 cal/lb/day). People with more muscle mass have higher BMRs. This is why BMI-based calculators may underestimate needs for muscular individuals and overestimate for those with high body fat percentage.
What is the best macronutrient ratio?
There is no single "best" ratio — it depends on your goals. A balanced starting point is 30% protein, 40% carbs, 30% fat. For weight loss, higher protein (35-40%) helps preserve muscle. For endurance athletes, higher carbs (50-60%) support performance. Adjust based on how you feel and perform.
Should I eat back exercise calories?
If using this calculator with an activity-adjusted TDEE, exercise calories are already included. Do not eat them back separately or you will overeat. If you use "Sedentary" and log exercise separately, eat back roughly 50-75% of estimated exercise calories (trackers tend to overestimate).