Calorie Calculator: BMR, TDEE, and Daily Calorie Needs
Your daily calorie requirement depends on more than your body weight. Age, sex, height, weight, and physical activity all affect how much energy your body uses. This calorie calculator estimates your basal metabolic rate (BMR), your total daily energy expenditure (TDEE), and practical calorie targets for maintaining, losing, or gaining weight.
The calculation uses the Mifflin–St Jeor equation for BMR and then applies an activity factor to estimate TDEE. The result is best treated as a useful starting estimate rather than a measurement of your exact metabolism.
02 · The Two NumbersBMR vs. TDEE: What Is the Difference?
BMR is the estimated amount of energy your body needs to support essential functions while at rest. It is not the number of calories you necessarily burn in a normal day because normal life includes movement, exercise, and the energy cost of processing food.
TDEE is an estimate of total daily energy expenditure after activity is taken into account. A simple version of the calculation is:
That makes TDEE the more useful starting point when you want to estimate a daily calorie intake for maintaining your current weight.
03 · CalculationHow the Calorie Formula Works
This calculator uses the Mifflin–St Jeor equation, a widely used predictive equation for resting energy expenditure.
After BMR is estimated, it is multiplied by the selected activity factor:
Worked example
For a 35-year-old person who is 175 cm tall and weighs 70 kg, the Mifflin–St Jeor equation first produces a BMR estimate. If the selected activity factor is 1.55, the TDEE is then calculated by multiplying that BMR by 1.55.
Step 2: Select the activity factor that matches normal activity.
Step 3: TDEE = BMR × activity factor.
Step 4: Use TDEE as the maintenance starting point.
04 · GoalsHow Many Calories Should You Eat to Lose or Gain Weight?
Once you have an estimated maintenance level, a calorie deficit means consuming less energy than you expend, while a calorie surplus means consuming more. The size of the gap affects the pace of expected weight change, but real-world results are not perfectly linear.
| Goal | Typical adjustment | Use |
|---|---|---|
| Maintain | ≈ TDEE | Start near estimated maintenance |
| Gradual loss | ≈ TDEE − 250 to 300 | Smaller calorie deficit |
| Moderate loss | ≈ TDEE − 500 | Common starting deficit |
| Gain | ≈ TDEE + 250 to 300 | Modest calorie surplus |
It is tempting to convert a calorie deficit directly into a guaranteed amount of weight loss. Real-world change is more complicated: water balance, appetite, activity, body composition, and metabolic adaptation can all shift the result. Use the calculated target as a starting range and judge it against your longer-term trend.
05 · ActivityChoosing the Right Activity Level
The activity multiplier is important because BMR only represents resting energy expenditure. Choosing an activity level that is too high can make the resulting TDEE estimate unnecessarily high.
| Activity level | Factor | General description |
|---|---|---|
| Sedentary | 1.20 | Little or no structured exercise |
| Light | 1.375 | Light exercise about 1–3 days/week |
| Moderate | 1.55 | Moderate exercise about 3–5 days/week |
| Active | 1.725 | Hard exercise about 6–7 days/week |
| Very active | 1.90 | Very hard training or substantial physical activity |
Activity descriptions are approximate. A workout schedule alone does not always describe your total daily movement, so use the level that most closely reflects your typical routine rather than your most active day.
06 · Interpreting ResultsWhy Your Actual Calorie Needs May Differ
Two people with the same age, height, weight, and sex can still have different energy requirements. Body composition, spontaneous movement, training volume, occupation, sleep, and other factors influence daily energy expenditure.
For that reason, the most useful way to use a calorie calculator is as a starting estimate. If you consistently follow a reasonable intake and your body weight changes differently from the expected direction, that observed trend can help you refine the estimate over time.
07 · FAQCalorie Calculator FAQs
In nutrition, the word “calorie” commonly refers to a kilocalorie (kcal). One kilocalorie is 1,000 small calories and is approximately 4.184 kilojoules.
TDEE is an estimate of the energy you expend each day. Your estimated maintenance intake is often set near that value, although actual maintenance can vary from day to day.
It is an estimate, not a laboratory measurement. The accuracy depends partly on the quality of the inputs, especially the activity level, and individual energy expenditure can differ from the equation.
No. Treat the result as a starting point. Your real-world weight trend and professional guidance, when appropriate, are more useful than assuming one calculated number is exact.
It can help estimate an energy target, but it does not create a nutritionally complete meal plan. Food quality, protein, fiber, vitamins, minerals, and individual dietary needs also matter.