How This Calculator Works
This calculator uses the Mifflin-St Jeor equation, which research has shown to be the most accurate BMR formula for most people. The American Dietetic Association recommended it over the older Harris-Benedict equation back in 2005, and it remains the clinical standard.
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
TDEE = BMR × Activity Multiplier
Activity Multipliers Explained
| Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Desk job, almost no exercise |
| Lightly active | 1.375 | Light exercise 1–3 days/week |
| Moderately active | 1.55 | Moderate exercise 3–5 days/week |
| Very active | 1.725 | Hard exercise 6–7 days/week |
| Extra active | 1.9 | Athlete-level or physical labor job + training |
Most people overestimate their activity level. If you work out 3 times a week but sit at a desk all day, "lightly active" is probably more accurate than "moderately active."
Weight Loss: The Calorie Deficit
One pound of body fat stores about 3,500 calories. To lose 1 pound per week, you need a daily deficit of roughly 500 calories below your TDEE. For 2 pounds per week, that deficit is 1,000 calories.
Going too aggressive has downsides: muscle loss, metabolic adaptation, fatigue, and nutrient deficiencies. Most nutritionists recommend staying above 1,200 calories/day (women) or 1,500 calories/day (men) without medical supervision.
Muscle Gain: Caloric Surplus
Building muscle requires a caloric surplus, but going overboard just adds fat. A surplus of 250–500 calories above your TDEE is enough for most people. Combine that with strength training and adequate protein (0.7–1 gram per pound of body weight).
Common Mistakes
- Not counting liquid calories. A daily latte and evening beer can easily add 400+ calories that many people forget to track.
- Overestimating exercise burn. A 30-minute jog burns roughly 250–350 calories. A single muffin puts those back.
- Ignoring portion sizes. A "serving" of peanut butter is 2 tablespoons (190 calories). Most people eat 3–4 tablespoons without measuring.
- Weekend eating. Five disciplined weekdays can be undone by two days of untracked eating. Consistency matters.
Macronutrient Breakdown
Calories come from three macronutrients, each serving a different role in your body:
| Macro | Calories/gram | Role | Recommended % |
|---|---|---|---|
| Protein | 4 cal/g | Muscle repair, satiety, immune function | 25–35% |
| Carbohydrates | 4 cal/g | Primary energy source, brain fuel | 40–55% |
| Fat | 9 cal/g | Hormone production, vitamin absorption | 20–35% |
For a 2,000 calorie diet with a 30/40/30 split (protein/carbs/fat): 150g protein, 200g carbs, and 67g fat per day.
Daily Calorie Needs by Activity Level (160 lb / 73 kg Male, Age 30)
Calorie Counting and Weight Plateaus
After weeks of a caloric deficit, your body adapts by lowering its metabolic rate — a process called metabolic adaptation (or “adaptive thermogenesis”). When progress stalls despite consistent effort, try these strategies:
- Recalculate TDEE: As you lose weight, your calorie needs decrease. A person who lost 20 lb needs to recalculate. Use this calculator with your current weight.
- Diet break (1–2 weeks at maintenance): Eating at maintenance temporarily can reset hunger hormones and reduce metabolic adaptation.
- Add resistance training: Building muscle increases resting metabolic rate. Even modest muscle gain burns 50–100 extra calories per day.
- Track more carefully: “Calorie creep” is common — portions gradually increase and tracking gets lax. Weigh food for a week to recalibrate.
Monitor body fat changes alongside weight. Our body fat calculator helps track composition changes, and BMI provides a quick reference for overall weight status.
Frequently Asked Questions
How to Use This Calorie Calculator
Enter your gender, age, height, weight, and activity level. The calculator shows your daily calorie needs for weight maintenance, loss, and gain.
Formula & How It Works
Uses Mifflin-St Jeor then multiplies by activity factor. Weight loss: subtract 500 cal/day for 1 lb/week loss. Weight gain: add 300-500 cal/day for lean muscle gain.
Calculation Example
Male, 30, 180 cm, 80 kg, moderately active: Maintenance = 2,680 cal. Weight loss = 2,180 cal. Muscle gain = 2,980-3,180 cal.
Expert Tips
A 500 cal/day deficit is safe and sustainable (~1 lb/week loss). Do not go below 1,200 cal (women) or 1,500 cal (men). Protein should be 25-30% of calories when dieting to preserve muscle.
How many calories should I eat per day?
There's no single number that fits everyone. Average adults need 1,600–2,400 calories (women) or 2,000–3,000 calories (men) per day, depending on age, size, and how active they are. This calculator gives you a personalized estimate based on your actual stats.
What is BMR vs. TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns doing absolutely nothing, like breathing and keeping your heart beating. TDEE (Total Daily Energy Expenditure) multiplies your BMR by an activity factor to give a more realistic daily calorie target. Use TDEE for diet planning, not BMR.
How do I lose 1 pound per week?
Eat about 500 calories fewer per day than your TDEE. That adds up to a 3,500-calorie deficit per week, which equals roughly 1 pound of fat. Combining diet with exercise makes this easier, since you can eat 300 fewer and burn 200 more, for example.
Is the Mifflin-St Jeor equation accurate?
It is the most accurate widely-used formula, within about 10% for most adults. However, it doesn't account for muscle mass, so very muscular or very obese individuals may get less accurate results. For those cases, body composition-based formulas like Katch-McArdle are better.
Should I eat back exercise calories?
If you chose an activity level that already reflects your exercise routine, your TDEE accounts for it. Eating those calories again would double-count them. Only add extra calories if you did activity beyond your selected level.