Free Calorie Calculator — Find Your Daily Calorie Needs for Weight Loss, Maintenance or Muscle Gain

Whether your goal is to lose weight, build muscle, or simply maintain a healthy body, understanding how many calories your body needs each day is the single most important starting point. Our free online Calorie Calculator uses the most accurate scientific formulas available — the Mifflin-St Jeor equation and the Harris-Benedict equation — to calculate your Basal Metabolic Rate and Total Daily Energy Expenditure based on your age, sex, height, weight, and physical activity level. The result is a personalised daily calorie target that you can use immediately to guide your nutrition decisions.

Everything runs entirely in your browser. No personal information you enter — your weight, height, age, or health goals — is sent to any server or stored anywhere. All calculations happen locally on your device, making this tool completely private and available even without an internet connection once the page has loaded.

What Is a Calorie and Why Does Counting Them Work?

A calorie — technically a kilocalorie in nutrition science — is a unit of energy. When you eat food, your body converts that food into energy it uses to power every biological process, from breathing and circulation to walking, thinking, and exercising. When you consume more energy than your body needs, the surplus is stored as body fat. When you consume less energy than your body needs, it draws on stored fat to make up the difference. This fundamental principle, known as the energy balance equation, is the biological basis for all evidence-based approaches to weight management.

Research published in major nutrition journals consistently confirms that a calorie deficit — consuming fewer calories than you expend — produces reliable weight loss regardless of which specific foods or macronutrient ratios are used to achieve it. Similarly, a calorie surplus reliably produces weight gain, which is essential information for individuals who want to build muscle mass and are struggling to consume enough food. Knowing your precise calorie target removes the guesswork and gives you a concrete number to work toward each day.

How the Calorie Calculator Works: BMR and TDEE Explained

The calculation proceeds in two steps. First, the calculator determines your Basal Metabolic Rate, or BMR. Your BMR is the number of calories your body burns simply to stay alive — maintaining organ function, regulating body temperature, keeping your heart beating, and all other involuntary processes — while at complete rest. This represents the minimum energy your body requires just to exist and typically accounts for sixty to seventy percent of total daily calorie expenditure for sedentary individuals.

The Mifflin-St Jeor equation, developed in 1990 and validated extensively since then, is widely considered the most accurate BMR formula for the general population. For men, it calculates: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5. For women, the formula is identical except the final constant is −161 rather than +5, accounting for the typically lower metabolic rate associated with female physiology. The tool also supports the older Harris-Benedict equation (1919, revised 1984) for comparison, as some users and practitioners prefer it.

The second step multiplies your BMR by an activity factor to produce your Total Daily Energy Expenditure, or TDEE. This is the total number of calories you actually burn across an entire day, including all physical activity on top of your resting metabolism. The activity multipliers range from 1.2 for sedentary individuals who do little or no deliberate exercise, through 1.375 for lightly active people who exercise one to three days per week, to 1.55 for moderately active individuals, 1.725 for very active people who exercise six to seven days per week, and 1.9 for those with extremely high activity levels such as athletes in twice-daily training or people with physically demanding occupations.

Calorie Targets for Every Goal: Weight Loss, Maintenance and Muscle Gain

Once your TDEE is known, setting a calorie target for any health goal is straightforward mathematics.

For weight loss: A deficit of 500 calories per day below your TDEE produces approximately 0.45 kilograms (one pound) of fat loss per week, since one pound of body fat contains roughly 3,500 calories. A deficit of 1,000 calories per day produces approximately one kilogram (two pounds) of fat loss per week. Most nutrition professionals recommend keeping deficits within the range of 500 to 750 calories per day to preserve muscle mass, maintain energy levels, and support long-term adherence. Very aggressive deficits exceeding 1,000 calories daily can cause muscle loss, fatigue, nutritional deficiencies, and metabolic adaptation.

For weight maintenance: Consuming calories equal to your TDEE keeps your body weight stable. This is your maintenance calories figure, and it serves as the anchor point for all other calorie targets. Our calculator displays this number prominently so you always have a reference point regardless of your chosen goal.

For muscle gain (bulking): A modest surplus of 250 to 500 calories above maintenance supports muscle growth while minimising unnecessary fat gain. This approach, sometimes called a lean bulk, is generally preferred over aggressive surpluses, which tend to produce more fat accumulation than additional muscle. The calculator provides both a moderate surplus option and a more aggressive surplus for those prioritising maximum muscle gain during dedicated bulking phases.

Macronutrient Breakdown: Protein, Carbohydrates and Fat

Knowing your total calorie target is only the first piece of the nutritional puzzle. How you distribute those calories among the three macronutrients — protein, carbohydrates, and fat — significantly affects your body composition results, energy levels, satiety, and athletic performance. Our calculator provides recommended macronutrient targets based on your goal and body weight.

Protein is the most important macronutrient for body composition. It preserves lean muscle mass during calorie deficits, stimulates muscle protein synthesis during surpluses, and produces a higher thermic effect than carbohydrates or fat, meaning the body burns more calories digesting it. Most evidence supports a protein intake of 1.6 to 2.2 grams per kilogram of body weight per day for individuals engaged in resistance training. Fat provides essential fatty acids and fat-soluble vitamins and should generally constitute at least 20 percent of total calories. Carbohydrates fill the remaining calories and serve as the primary fuel source for high-intensity exercise.

Body Mass Index, Ideal Body Weight and Healthy Weight Range

In addition to calorie targets, our calculator computes your Body Mass Index using the standard formula of weight in kilograms divided by height in metres squared, and displays your current BMI classification alongside the healthy weight range for your height. While BMI is a useful population-level screening tool, it does have well-known limitations — it does not distinguish between muscle mass and fat mass, for instance — and should be interpreted alongside other health markers rather than used in isolation. The ideal body weight estimate uses the Devine formula, which is widely used in clinical settings as a reference point for medication dosing and health benchmarking.

Use our free Calorie Calculator today to discover your personalised daily calorie needs, set a goal-specific calorie target, and get a macronutrient breakdown to support your weight loss, maintenance, or muscle-building journey. No account required, no data collected, and no cost — just accurate, science-based results in seconds.