Calorie Calculator
This free calorie calculator estimates how many calories you burn in a day, based on your age, gender, height, weight, and activity level, then shows calorie targets for common weight loss and weight gain goals. Nothing you enter is sent anywhere or stored.
How to Use It
- Enter your age and select your gender.
- Choose US / Imperial or Metric units, then enter your height and weight.
- Select your activity level.
- Your maintenance calories and weight loss/gain targets appear instantly as you type.
How It Works
This calculator first estimates your BMR using the Mifflin-St Jeor equation, the modern standard for this kind of estimate. It multiplies your weight and height by fixed factors, then subtracts a factor based on your age, adding a small constant for men and subtracting a larger one for women, since typical body composition differs by gender.
That BMR is then multiplied by an activity factor to get your maintenance calories, the number you'd need to eat daily to maintain your current weight:
| Activity level | Multiplier |
|---|---|
| Sedentary (little or no exercise) | ×1.2 |
| Lightly active (1 to 3 days/week) | ×1.375 |
| Moderately active (3 to 5 days/week) | ×1.55 |
| Very active (6 to 7 days/week) | ×1.725 |
| Extra active (hard exercise and a physical job) | ×1.9 |
Formulas
BMR (men) = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
BMR (women) = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
maintenance calories = BMR × activity multiplier
The weight loss and weight gain figures are that maintenance number plus or minus a fixed calorie offset, based on the common estimate that a pound of body weight is roughly 3,500 calories.
A worked example: a 30-year-old man who is 180 cm tall and weighs 80 kg has a BMR of 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 1,780 calories. At a moderately active level (×1.55), that gives maintenance calories of 1,780 × 1.55 ≈ 2,759. A mild weight-loss target (−250/day) comes out to about 2,509 calories, and a standard weight-loss target (−500/day) to about 2,259.
BMI and calorie needs are related but answer different questions. See our guide, BMI Explained: What It Measures, and Where It Falls Short, for how BMI fits alongside a calorie estimate like this one.
Everything runs client-side in your browser. No measurements you enter are sent anywhere or stored.
Frequently Asked Questions
What are BMR and TDEE?
BMR (Basal Metabolic Rate) is roughly how many calories your body burns at complete rest, just keeping you alive. TDEE (Total Daily Energy Expenditure), shown here as your maintenance calories, adds your activity level on top of that, so it's a more realistic estimate of what you actually burn in a day.
Why does this calculator need my age and gender?
Unlike a BMI calculation, the formula used here (Mifflin-St Jeor) takes age and biological sex as direct inputs, since metabolic rate genuinely differs by both. Changing either one changes the calorie estimate, not just a note alongside it.
Are the weight loss and weight gain numbers exact?
No, they're estimates. They're based on the common rule of thumb that a pound of body weight is roughly 3,500 calories, applied as a fixed daily offset from your maintenance calories. Actual results vary by individual and tend to slow down over time, so treat these as a starting point, not a guarantee.
Why does Mifflin-St Jeor replace the older Harris-Benedict formula?
Mifflin-St Jeor was published in 1990 and validated against a more modern population than the original 1919 Harris-Benedict equation, and has since been shown in multiple studies to predict resting metabolic rate more accurately for most people. It's now the formula most dietitians and nutrition guidelines default to, which is why it's the one used here.
How is this different from the BMI Calculator?
BMI only uses height and weight to estimate a weight category. This calculator estimates an actual daily calorie number, using height, weight, age, gender, and activity level together. It answers a different question (how much energy you need) rather than BMI's question (which weight category you fall into). See our BMI guide (linked below) for more on what BMI does and doesn't capture.
Should the extreme weight loss option be used long-term?
Generally no. The 1,000-calorie-per-day deficit option is a faster-loss estimate, not a recommendation to sustain indefinitely. A large sustained deficit is harder to stick with and more likely to affect energy levels and muscle mass than a smaller one. The mild or standard loss options are more commonly recommended for a sustainable long-term pace.
Does this account for muscle mass or body fat percentage?
No, like BMI, this formula only takes height, weight, age, and gender as inputs, not body composition. Two people with identical height, weight, age, and gender but very different muscle-to-fat ratios will get the same BMR estimate here, even though a more muscular person typically burns somewhat more at rest. It's a solid population-level estimate, not a personalized metabolic test.