How to use this calculator
Select your unit system (Imperial or Metric), then enter your gender, age, height, and weight. Choose the activity level that best describes your typical week. The calculator instantly shows your Basal Metabolic Rate (BMR), daily maintenance calories, and calorie targets for weight loss or gain.
Be honest about your activity level, it's the input people most commonly overestimate. If you work a desk job and exercise 3 times per week, "Moderately Active" is likely the right choice, not "Very Active."
Understanding BMR and TDEE
Your Basal Metabolic Rate (BMR) is the number of calories your body needs just to stay alive, breathing, pumping blood, maintaining body temperature, and repairing cells. Even if you stayed in bed all day, your body would still burn this many calories.
Your Total Daily Energy Expenditure (TDEE) adds your physical activity on top of BMR. This is the number that actually matters for weight management. Eat below your TDEE to lose weight, match it to maintain, or exceed it to gain.
This calculator uses the Mifflin-St Jeor equation, which research has shown to be the most accurate BMR formula for most people. It replaced the older Harris-Benedict equation, which tends to overestimate calorie needs by 5-15%.
How calorie deficits work
One pound of body fat contains roughly 3,500 calories. To lose one pound per week, you need a daily deficit of about 500 calories below your TDEE. A 1,000-calorie deficit targets two pounds per week, though this more aggressive approach can be harder to sustain.
Most health professionals recommend staying above 1,200 calories per day for women and 1,500 for men to ensure adequate nutrition. Going below these thresholds without medical supervision can lead to nutrient deficiencies, muscle loss, metabolic slowdown, and other health issues.
Activity level multipliers
| Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2x | Little to no exercise, desk job, minimal daily movement. |
| Lightly Active | 1.375x | Light exercise or walking 1-3 days per week. |
| Moderately Active | 1.55x | Moderate exercise 3-5 days per week. |
| Very Active | 1.725x | Hard exercise or sports 6-7 days per week. |
| Extra Active | 1.9x | Very intense exercise, physical job, or training twice daily. |
Frequently asked questions
How many calories should I eat per day?
It depends on your age, gender, size, and activity level. Most adults need between 1,600 and 3,000 calories per day to maintain their weight. Use this calculator to get a personalized estimate based on the Mifflin-St Jeor equation.
What is the Mifflin-St Jeor equation?
It's the most widely recommended formula for estimating BMR. For men: 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5. For women: the same formula but subtracting 161 instead of adding 5. It was developed in 1990 and is considered more accurate than the older Harris-Benedict equation.
How many calories should I cut to lose weight?
A deficit of 500 calories per day below your TDEE leads to roughly 1 pound of weight loss per week. A 1,000-calorie deficit targets 2 pounds per week but is more aggressive and harder to sustain. Most experts recommend the moderate approach for long-term success.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is what your body burns at complete rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by your activity level, it's the total calories you burn in a day including exercise and daily movement. TDEE is the number you should base your calorie goals on.