Calorie Calculator

Quick answer: Calorie Calculator is a free online tool that lets you enter your age, sex, height, weight, and activity level to estimate how many calories you burn per day — plus target intakes for losing, maintaining, or gaining weight. No account or install needed — it runs entirely in your browser, free.

Enter your age, sex, height, weight, and activity level to estimate how many calories you burn per day — plus target intakes for losing, maintaining, or gaining weight.

What is the Calorie Calculator?

A calorie calculator estimates how many calories your body burns each day, so you can eat the right amount for your goal. It starts with your BMR (basal metabolic rate), the energy you burn at complete rest, computed with the Mifflin-St Jeor equation, the formula most dietitians consider the most accurate for the general population. It then multiplies your BMR by an activity factor to get your TDEE (total daily energy expenditure), your true daily burn including movement and exercise.

From there the math of weight change is straightforward: eat below your TDEE to lose weight, match it to maintain, or exceed it to gain. A daily deficit of about 500 calories typically produces roughly half a kilogram (one pound) of fat loss per week, because a kilogram of body fat stores around 7,700 calories. This calculator shows ready-made targets for slow, moderate, and faster loss, plus gentle surplus targets for healthy weight gain.

These are well-validated estimates, but they are still estimates. Metabolism varies with muscle mass, hormones, medications, and medical conditions, and very low intakes can be unsafe. Treat the numbers as a starting point, adjust based on real-world results over two to three weeks, and consult a qualified professional before making major dietary changes.

How to use the Calorie Calculator

  1. Enter your age in years. Calorie needs decline slowly with age as metabolism and muscle mass change.
  2. Select your sex. The Mifflin-St Jeor equation uses different constants for men and women.
  3. Enter your height in centimeters and your current weight in kilograms.
  4. Choose the activity level that best matches your typical week, including both exercise and daily movement.
  5. Click Calculate Calories. Your BMR and TDEE appear at the top, with goal-based targets in the table.
  6. Pick the target matching your goal and track your weight for two to three weeks, then adjust up or down as needed.

Calorie Calculator use cases

Starting a weight-loss plan

Every successful diet begins with knowing your maintenance calories. The calculator gives you that anchor number plus sensible deficit targets, so instead of guessing at 1,200 or 1,500 calories, you start from a figure grounded in your actual body size and activity level.

Breaking through a plateau

When weight loss stalls, the usual culprit is that a lighter body burns fewer calories than when you started. Re-running the calculator at your new weight reveals your updated TDEE and shows exactly how much to trim to restart progress.

Fueling athletic training

Runners, lifters, and team-sport athletes often under-eat without realizing it, which tanks performance and recovery. Matching intake to the active or extra-active TDEE estimate ensures training is fueled, while the gain targets support deliberate muscle building phases.

Healthy weight gain

Gaining weight well means a modest surplus, not an all-you-can-eat free-for-all. The calculator’s +250 and +500 targets add roughly a quarter to half a kilogram per week, which favors muscle over fat when paired with resistance training.

Maintaining after a diet

The hardest phase of weight loss is keeping it off. Knowing your true maintenance TDEE at your new weight gives you a concrete daily budget to live within, which is far more sustainable than staying on a deficit forever.

Tips

  • Be honest about activity level. Most people overestimate it; when in doubt, pick one level lower and adjust based on results.
  • Weigh and measure food for at least two weeks when starting. Studies show people underestimate intake by 20 to 40 percent without measuring.
  • Never drop below 1,200 calories per day (women) or 1,500 (men) without medical supervision. Very low intakes risk nutrient deficiencies and muscle loss.
  • Recalculate every 5 kg of weight change. A smaller body burns less, so targets that worked at the start will eventually become maintenance.
  • These are estimates for informational purposes. For medical conditions, pregnancy, or major dietary changes, consult a qualified professional.

Frequently asked questions

What is the Mifflin-St Jeor equation?
It is a formula that predicts basal metabolic rate from sex, age, height, and weight. For men it is 10 times weight in kg plus 6.25 times height in cm minus 5 times age plus 5; for women the constant is minus 161 instead of plus 5. Published in 1990 and validated against measured metabolism, it is considered more accurate than the older Harris-Benedict equation for most modern adults.
What is the difference between BMR and TDEE?
BMR, or basal metabolic rate, is the calories you would burn lying completely still all day just keeping your organs running. TDEE, total daily energy expenditure, is your BMR multiplied by an activity factor covering everything else: walking, working, fidgeting, and exercise. Your TDEE is the number that actually determines whether you lose, maintain, or gain weight.
How many calories should I eat to lose weight?
A moderate deficit of about 500 calories below your TDEE typically yields roughly half a kilogram of fat loss per week, which most guidelines consider a safe, sustainable rate. The calculator shows 250, 500, and 750 calorie deficits so you can choose your pace. Faster loss sounds appealing but is harder to sustain and risks more muscle loss.
Why am I not losing weight at my target calories?
The most common reasons are undercounted intake, an overestimated activity level, or water retention masking fat loss on the scale. Track food honestly with a scale for two weeks, make sure your activity choice reflects reality, and judge by the trend over several weeks rather than day-to-day readings before adjusting your target.
Should athletes use the highest activity level?
Only if the description truly fits. Extra active is meant for people with physical jobs or athletes training intensely most days plus high daily movement. A desk worker who lifts three times a week is moderately active, not extra active. Choosing too high a level inflates your TDEE and quietly erases your deficit.
Do I need to eat back exercise calories?
If your activity level already accounts for your exercise, no, eating back the calories your watch reports would double-count them. Fitness trackers also tend to overestimate burn. The cleanest approach is to pick one activity level, eat to that target consistently, and adjust based on your weight trend.
Are 1,200-calorie diets safe?
Very low calorie intakes can cause nutrient deficiencies, muscle loss, hormonal disruption, and gallstones, and they are rarely sustainable. General guidance suggests not dropping below 1,200 calories for women or 1,500 for men without medical supervision. If the calculator's loss targets fall below those floors, choose the slowest loss rate and talk to a professional.
How accurate is this calculator?
The Mifflin-St Jeor equation predicts BMR within about 10 percent for most people, which is good for a formula but not perfect. Individual metabolism varies with muscle mass, genetics, hormones, and medications. Treat the result as a well-grounded starting point, then fine-tune based on your actual weight trend over two to three weeks.