Calorie Calculator: BMR, TDEE and Goal Calories
Estimate your BMR, maintenance calories (TDEE) and daily calories to lose or gain 0.25, 0.5 or 1 kg a week with the Mifflin-St Jeor, revised Harris-Benedict or Katch-McArdle equation, in kcal or kJ, metric or US units. Nothing is sent anywhere.
Enter your age, height and weight to see your calories.
About the Calorie Calculator
The Calorie Calculator estimates how many calories you use in a day and how many to eat to keep, lose or gain weight. Enter your age, sex, height and weight, choose how active you are, and it shows three things: your basal metabolic rate (BMR), the energy your body uses at complete rest; your maintenance calories, also called total daily energy expenditure (TDEE); and a daily calorie figure for six goals, from extreme weight loss to extreme weight gain.
Heights and weights can be typed in centimetres and kilograms or in feet, inches and pounds, and every result can be shown in kilocalories (kcal) or kilojoules (kJ). Nothing is uploaded: every calculation runs in your browser and the numbers you type never leave your device.
This is an estimate, not medical advice. The equations predict the average for people of your size and age, and your own needs can differ by 10 percent or more. Talk to a doctor or a registered dietitian before a large change in what you eat, and especially before eating below the floor the calculator warns about.
How to use it
Steps
- Choose metric or US customary units, then your sex.
- Enter your age, height and weight. Body fat percentage is optional and only needed for the Katch-McArdle equation.
- Pick the activity level that best matches a normal week.
- Read your BMR, your maintenance calories and the goal table.
Which equation
Mifflin-St Jeor is the default; in comparison studies it predicts measured resting energy most closely for most adults. The revised Harris-Benedict equation is the older standard, refitted in 1984. Katch-McArdle uses lean body mass instead of height, sex and age, so it suits people who know their body fat percentage, such as athletes.
The formulas
With weight in kilograms, height in centimetres and age in years:
Maintenance calories are BMR multiplied by an activity factor: 1.2 for sedentary, 1.375 for lightly active, 1.55 for moderately active, 1.725 for very active and 1.9 for extra active. These multipliers are a long-standing convention in dietetics rather than the result of a single study.
Goal calories and the 7,700 kcal rule
The goal table assumes that one kilogram of body weight holds about 7,700 kcal. Losing or gaining 0.25, 0.5 or 1 kg a week therefore means eating about 275, 550 or 1,100 kcal a day less or more than maintenance. The rule is a simplification: as you lose weight your maintenance calories fall, so progress usually slows over time.
Any goal below 1,200 kcal a day for women or 1,500 kcal a day for men is flagged. Intakes below these levels make it hard to get enough protein, vitamins and minerals and are normally followed only under medical supervision.
Worked example
A 30-year-old man, 180 cm tall and weighing 80 kg, has a Mifflin-St Jeor BMR of 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 1,780 kcal a day. If he is moderately active, his maintenance calories are 1,780 × 1.55 = 2,759 kcal a day, and losing 0.5 kg a week means about 2,209 kcal a day.
Related tools
Focus on the resting figure with the BMR Calculator, compare activity levels with the TDEE Calculator, or split your calories into protein, carbohydrate and fat with the Macro Calculator. Check where your weight sits with the BMI Calculator, and convert pounds to kilograms with the Mass Converter.
Sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition 1990;51(2):241–247.
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. American Journal of Clinical Nutrition 1984;40(1):168–182.
- McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy, and Human Performance. Lippincott Williams & Wilkins (the Katch-McArdle equation).
Open-source credits
The calculations are implemented in-house in TypeScript, with no third-party libraries. They follow the published Mifflin-St Jeor (1990), revised Harris-Benedict (Roza and Shizgal, 1984) and Katch-McArdle equations, the conventional activity factors and the 7,700 kcal per kilogram rule.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR, basal metabolic rate, is the energy your body uses at complete rest just to stay alive. TDEE, total daily energy expenditure, adds everything else: walking, exercise, work and digesting food. TDEE is BMR times an activity factor from 1.2 for sedentary to 1.9 for extra active, and it is the figure that keeps your weight steady.
Which BMR equation should I choose?
Mifflin-St Jeor is the default because comparison studies found it predicts measured resting energy most closely for most adults. The revised Harris-Benedict equation is the older standard and usually gives a slightly higher figure. Katch-McArdle uses lean body mass, so pick it if you know your body fat percentage, especially if you are lean or muscular.
How many calories should I cut to lose weight?
The calculator assumes one kilogram of body weight holds about 7,700 kcal, so losing 0.25, 0.5 or 1 kg a week means eating about 275, 550 or 1,100 kcal a day below maintenance. A loss of about 0.5 kg a week is a common, sustainable pace. As you lose weight your maintenance calories fall, so recalculate every few kilograms.
Why does the calculator warn below 1,200 or 1,500 calories?
Eating less than about 1,200 kcal a day for women or 1,500 kcal a day for men makes it hard to get enough protein, vitamins and minerals, and very low intakes are normally followed only under medical supervision. The goal table flags any row below these levels so you can choose a slower pace instead.
How do I convert kcal to kJ?
One kilocalorie is 4.184 kilojoules, so 2,000 kcal is 8,368 kJ. Switch the energy unit to kJ and every figure on the page, including the goal table, is shown in kilojoules. Food labels in Australia, New Zealand and the EU often show kJ, while the United States and the UK usually use kcal, written as Calories.
Is my data stored or sent anywhere?
No. Every calculation runs in your browser, nothing is sent to a server, and the numbers you type disappear when you close the page.