The Short Answer
Your daily calorie needs depend on two things:
- BMR (Basal Metabolic Rate) — calories your body burns at rest
- Activity level — calories burned through movement and exercise
TDEE = BMR × Activity Multiplier
TDEE (Total Daily Energy Expenditure) is the total number of calories you burn in a day.
Calculate Your TDEE
Use our calorie calculator to get your personalized number:
How BMR Is Calculated
The most widely used formula is the Mifflin-St Jeor equation (1990), which research has shown to be the most accurate for most people:
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
Example
A 30-year-old man, 180 cm tall, weighing 80 kg:
- BMR = (10 × 80) + (6.25 × 180) - (5 × 30) + 5
- BMR = 800 + 1,125 - 150 + 5
- BMR = 1,780 calories/day
This means his body burns 1,780 calories just to stay alive — breathing, circulation, cell repair, temperature regulation.
Activity Multipliers
Your BMR is just the starting point. Multiply it by your activity level to get your TDEE:
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Desk job, little 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 or very physical job |
Using our example: 1,780 × 1.55 (moderately active) = 2,759 calories/day
Calorie Targets by Goal
Once you know your TDEE, adjust based on your goal:
| Goal | Daily Calories | Rate |
|---|---|---|
| Lose weight (slow) | TDEE - 250 | ~0.5 lb/week |
| Lose weight (moderate) | TDEE - 500 | ~1 lb/week |
| Lose weight (aggressive) | TDEE - 750 | ~1.5 lb/week |
| Maintain weight | TDEE | Stable |
| Gain muscle (lean) | TDEE + 250 | ~0.5 lb/week |
| Gain weight | TDEE + 500 | ~1 lb/week |
The 500-calorie rule: A 500 calorie daily deficit equals roughly 1 pound of fat loss per week (3,500 calories = 1 lb of fat). This is a simplification, but it's a useful guideline.
Common Mistakes
1. Overestimating Activity Level
Most people overestimate how active they are. If you work out 3 times a week but sit at a desk the rest of the time, you're "lightly active," not "moderately active."
Tip: Start with the lower activity level and adjust based on actual results after 2 weeks.
2. Ignoring Non-Exercise Activity
NEAT (Non-Exercise Activity Thermogenesis) — fidgeting, walking, standing, cooking — can account for 200-800 calories per day. This is why some people seem to "eat whatever they want" without gaining weight.
3. Cutting Too Many Calories
Going below 1,200 (women) or 1,500 (men) calories per day is generally not recommended without medical supervision. Extreme deficits:
- Slow your metabolism
- Cause muscle loss
- Trigger nutrient deficiencies
- Are unsustainable (leading to binge cycles)
4. Not Adjusting Over Time
As you lose weight, your BMR decreases. A person who was 200 lbs and is now 170 lbs needs fewer calories. Recalculate every 10-15 lbs lost.
Macronutrient Breakdown
Calories matter for weight, but macros matter for body composition:
| Macro | Calories/gram | Recommended Range |
|---|---|---|
| Protein | 4 | 25-35% of calories |
| Carbohydrates | 4 | 35-50% of calories |
| Fat | 9 | 20-35% of calories |
For a 2,500 calorie diet:
- Protein: 156-219g (625-875 cal)
- Carbs: 219-313g (875-1,250 cal)
- Fat: 56-97g (500-875 cal)
Protein is king for body composition. Whether losing fat or building muscle, aim for at least 0.7g per pound of body weight.
How to Track Accurately
- Use a food scale — Eyeballing portions is notoriously inaccurate. A "tablespoon" of peanut butter can easily be 2-3 tablespoons.
- Track everything — Including cooking oils, condiments, and drinks. These add up fast.
- Be consistent — Track for at least 2 weeks before making adjustments.
- Weigh yourself consistently — Same time, same conditions (morning, after bathroom, before food).
- Use weekly averages — Daily weight fluctuates. The trend over 7 days is what matters.
Key Takeaways
- TDEE = BMR × Activity Multiplier — this is your daily calorie need
- Mifflin-St Jeor is the most accurate BMR formula for most people
- A 500 cal/day deficit ≈ 1 lb of fat loss per week
- Start conservative — overestimating activity is the #1 mistake
- Don't drop below 1,200/1,500 calories without medical guidance
- Recalculate as your weight changes
- Protein intake matters as much as total calories for body composition