Calorie and BMR Calculator
Estimate your basal metabolic rate (BMR) and daily energy expenditure from age, weight, height and activity level.
Fill in age, weight and height.
Estimate using the Mifflin-St Jeor formula, for informational purposes. Real needs vary from person to person; for any eating plan, consult a registered dietitian or doctor.
How it works
The tool estimates two numbers. The first is your basal metabolic rate (BMR): the energy your body uses at complete rest just to stay alive — breathing, keeping warm, keeping the heart beating. The second is your daily energy expenditure, which adds to the BMR the energy spent on your daily activities.
The BMR is calculated with the Mifflin-St Jeor formula, one of the most widely accepted today, using sex, age, weight and height. A factor based on your activity level — from sedentary to very active — is then applied to reach the estimated daily expenditure. You can enter measurements in metric or imperial units.
Fill in the fields, choose the activity level closest to your routine, and the two numbers appear instantly. These are reference estimates, useful for getting a general sense of how much energy your body uses.
When to use
Knowing your daily energy expenditure helps you understand your own metabolism and gives you an informed starting point for conversations about food and physical activity. It's a number that shows up in assessments by trainers and dietitians and in workout planning.
It works as a reference for understanding why energy needs vary so much between people: age, body size and activity level all change the result considerably. For any specific goal involving food, the best use of this estimate is as a basis for a conversation with a health professional, who will consider your full context.
Practical examples
A moderately active adult
A man aged 30, 165 lb and 5'10" with moderate activity has a BMR of around 1,700 kcal/day and an estimated daily expenditure near 2,640 kcal/day. The larger number already includes the energy spent on daily activities.
The weight of activity level
Keeping the same data and changing only the activity level, from sedentary to active, raises the estimated daily expenditure substantially. It shows how movement directly influences the total energy used in a day.
Common mistakes
The most common mistake is treating the result as an exact, universal number. These formulas are statistical estimates: a given person's real need can be higher or lower, because factors like body composition, genetics and health influence metabolism and aren't part of the calculation.
Another point is overestimating your own activity level. Many people classify themselves as "moderate" or "active" when their real routine is lighter, which inflates the estimated daily expenditure. Being honest with that choice keeps the number closer to reality.
Finally, remember this is an informational tool, not a meal plan. Setting eating goals on your own, from an estimated number, may not be appropriate or healthy. For that, guidance from a registered dietitian or doctor makes all the difference.
Frequently asked questions
What is basal metabolic rate (BMR)?
It's the amount of energy the body uses at complete rest just to keep vital functions going, like breathing, circulation and temperature. It's the foundation of daily energy expenditure.
Which formula does the calculator use?
The Mifflin-St Jeor formula, one of the most accepted today for estimating BMR. It uses sex, age, weight and height, and tends to give results close to those observed in practice.
Why is my expenditure different from someone else's at the same weight?
Because age, height, sex and, above all, activity level have a big influence. Body composition and genetics also affect metabolism and aren't captured by the formula.
Can I use this number for a diet?
Use it as a reference, not a plan. For eating goals, it's best to see a registered dietitian or doctor, who will consider your full context and define what's safe for you.