Calorie Calculator
Daily calorie needs based on age, activity, and goals.
Daily calorie needs
2,693 kcal
A calorie calculator estimates how many calories your body uses in a day, then translates that into targets for losing, maintaining, or gaining weight.
Enter your age, sex, height, weight, and activity level. The tool calculates your baseline needs and your total daily energy expenditure, then suggests calorie goals for common objectives.
Calorie needs are estimates that vary from person to person. They are a solid starting point, but real-world results depend on adjusting based on how your weight actually responds over a few weeks.
How this calculator works
The calculator finds your basal metabolic rate (BMR), the energy you burn at rest, using the Mifflin-St Jeor equation, which factors in weight, height, age, and sex. It then multiplies BMR by an activity factor (from about 1.2 for sedentary to 1.9 for very active) to estimate total daily energy expenditure (TDEE), the calories you burn on a typical day. To change weight, you adjust intake relative to TDEE: a deficit of about 500 calories a day targets roughly one pound of loss per week, since a pound of fat is about 3,500 calories, while a similar surplus supports gradual gain.
Assumptions and data behind the estimate
The calculator estimates your basal metabolic rate with the Mifflin-St Jeor equation from age, sex, height, and weight, multiplies it by an activity factor to approximate total daily energy expenditure, and applies a calorie deficit or surplus for weight goals using the rule of thumb that a pound of fat is about 3,500 calories. These equations are population averages and can be off by a few hundred calories for any individual, and metabolism adapts as weight changes. Use the number as a starting point and adjust based on how your weight actually trends over two to three weeks.
What affects the number
- Body size and composition matter; more muscle and greater weight raise your baseline calorie burn.
- Activity level is the biggest variable people control, spanning exercise and everyday movement.
- Age gradually lowers metabolic rate, so needs tend to decline over the decades.
- Sex affects the estimate because of differences in average body composition.
- The size of your deficit or surplus sets the pace of change; larger is faster but harder to sustain.
- These are estimates; tracking your weight trend over two to three weeks is the real calibration.
Frequently asked questions
How many calories should I eat to lose weight?
A common approach is to eat about 500 calories below your TDEE for roughly one pound of loss per week. More aggressive deficits speed things up but are harder to maintain and can cost muscle. Adjust based on how your weight actually trends over a few weeks.
What is TDEE?
TDEE is total daily energy expenditure, the calories you burn in a day from your resting metabolism plus activity and digestion. It is your maintenance level: eat at TDEE to hold weight, below it to lose, above it to gain.
How accurate is a calorie calculator?
Equations like Mifflin-St Jeor are good population estimates but can be off for any individual by a few hundred calories. Use the number as a starting point, then adjust intake based on real changes in your weight over two to three weeks.
Is a pound really 3,500 calories?
The 3,500-calories-per-pound figure is a longstanding rule of thumb for body-fat energy. It is a simplification, since metabolism adapts as you lose weight, but it remains a reasonable planning estimate for setting a weekly deficit.
Sources and references
- CDC - healthy weight and calorie balance
- National Institutes of Health - body weight and energy balance
This calculator provides general estimates for educational purposes only and is not financial, medical, legal, or tax advice. Your actual results depend on your specific situation and current rates.