How Many Calories Do You Really Need Each Day?
Your daily calorie needs come down to two numbers: how many calories your body burns at rest (your BMR), and how many extra calories your daily activity adds on top of that (giving you your TDEE — Total Daily Energy Expenditure). Once you know your TDEE, weight management becomes simple math: eat around that number to maintain weight, eat below it to lose weight, or eat above it to gain weight.
This calculator uses the Mifflin-St Jeor equation, one of the most widely used and researched formulas for estimating calorie needs, and applies an activity multiplier based on how active you actually are day to day. For a related measure of body composition, you can also check our BMI calculator.
BMR vs. TDEE: What's the Difference?
| Term | What It Measures | Includes Activity? |
|---|---|---|
| BMR (Basal Metabolic Rate) | Calories burned at complete rest to keep your body functioning | No |
| TDEE (Total Daily Energy Expenditure) | Total calories burned in a full day, including movement and exercise | Yes |
The Mifflin-St Jeor Equation:
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
TDEE = BMR × Activity Multiplier
Understanding Activity Levels
| Activity Level | Multiplier | Typical Lifestyle |
|---|---|---|
| Sedentary | 1.2 | Desk job, little to no structured exercise |
| Lightly active | 1.375 | Light exercise or sports 1-3 days a week |
| Moderately active | 1.55 | Moderate exercise or sports 3-5 days a week |
| Very active | 1.725 | Hard exercise or sports 6-7 days a week |
| Extra active | 1.9 | Very intense daily training or a physically demanding job |
Example Calculation
A 30-year-old woman weighing 65 kg and 165 cm tall, who exercises moderately 3-5 days a week, would calculate her needs like this:
- BMR = (10 × 65) + (6.25 × 165) − (5 × 30) − 161 = 1,395 kcal
- TDEE = 1,395 × 1.55 = ~2,162 kcal/day to maintain weight
- To lose weight: 2,162 − 500 = ~1,662 kcal/day
- To gain weight: 2,162 + 500 = ~2,662 kcal/day
Calorie Deficit and Surplus, Explained
Roughly 3,500 calories is equivalent to about one pound (0.45 kg) of body fat. A deficit of 500 calories a day, sustained over a week, works out to approximately one pound of weight loss — which is why 500 kcal is a common starting point for a moderate, sustainable deficit.
- To lose weight: eat 300-500 kcal below TDEE for gradual, sustainable loss.
- To maintain weight: eat close to your TDEE.
- To gain weight: eat 300-500 kcal above TDEE, paired with resistance training to favor muscle gain over fat gain.
Avoid extreme deficits. Cutting more than 1,000 calories a day or dropping below general minimum thresholds (commonly cited as around 1,200 kcal/day for women and 1,500 kcal/day for men) can lead to nutrient deficiencies, muscle loss, and a slower metabolism. Very low-calorie diets should only be followed under medical supervision.
Common Mistakes People Make With Calorie Targets
- Not recalculating after weight change: your BMR drops as you lose weight, so a target that worked at the start can stall progress later.
- Underestimating portion sizes: even accurate calorie targets fail if food intake isn't tracked reasonably closely.
- Overestimating activity level: most people overstate how active they are, which inflates the calculated TDEE.
- Cutting calories too aggressively: large deficits are harder to sustain and more likely to cause muscle loss.
- Ignoring protein intake: adequate protein helps preserve muscle mass during a deficit and supports muscle growth during a surplus.
Tip: Treat your calculated TDEE as a starting point, not a fixed number. Track your weight over 2-3 weeks and adjust your intake by 100-150 calories if your progress is faster or slower than expected.
Frequently Asked Questions
It depends on your gender, age, height, weight, and activity level. This calculator estimates your BMR using the Mifflin-St Jeor equation, then multiplies it by an activity factor to get your TDEE. Most adults need between 1,600 and 3,000 calories daily, but your exact number depends on your personal stats and goal.
BMR is the number of calories your body burns at complete rest just to stay alive. TDEE adds your activity level on top of BMR, giving you the total calories you burn in a full day, including exercise and daily movement.
A deficit of about 500 calories per day below your TDEE is a common starting point, since roughly 3,500 calories equals about one pound of body fat. This typically results in about 0.5-1 kg (1-2 lb) of weight loss per week. Avoid cutting more than 1,000 calories a day without medical supervision.
It's considered one of the more reliable formulas for estimating BMR in the general population, typically landing within about 10% of measured energy needs. It's still an estimate — actual needs vary with muscle mass, genetics, and health conditions, so results are best tracked and adjusted over a few weeks.
Either approach can work. A consistent daily target is simpler to follow, while calorie cycling (more on active days, less on rest days) suits people with variable training schedules. What matters most is your average weekly intake relative to your TDEE.
As you lose or gain weight, your BMR changes because your body mass changes, and your activity level may shift too. Recalculating every few weeks, or whenever your weight changes by around 2-5 kg, keeps your target accurate to your current body.
Note: This calculator provides an estimate based on established population formulas. It is not a substitute for personalized advice from a registered dietitian or physician, especially if you have a medical condition, are pregnant or breastfeeding, or are managing a chronic illness.
