Find your Basal Metabolic Rate — the calories your body burns at rest — and your estimated total daily calorie needs, with the result updating live as you type.
BMR is the energy you use at complete rest. Maintenance (TDEE) is your BMR scaled by activity — the calories to keep your weight steady. These are estimates, not personal targets.
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest just to stay alive. Even if you spent all day lying still, your body would use this energy to power breathing, blood circulation, temperature control, brain activity and constant cell repair. For most people, BMR is the single largest part of daily energy use, usually around 60 to 70 percent of the total calories burned in a day.
This calculator estimates your BMR from your age, sex, height and weight, then multiplies it by an activity factor to estimate your total daily calorie needs. The body figure scales with your size, and the ring shows how much of your daily energy comes from resting metabolism versus movement.
Tip: pair this with our BMI Calculator to see both your body mass index and your daily energy needs in one place.
These three terms are related but not identical. BMR is measured under strict resting conditions and is the purest measure of resting energy. RMR (Resting Metabolic Rate) is measured under less strict conditions and is usually slightly higher, but the two are often used interchangeably. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor, so it estimates everything you burn in a day, including exercise and daily movement.
Our calculator relies on validated equations developed by physiological researchers. The Mifflin–St Jeor equation is the modern clinical standard and powers the result above; the revised Harris–Benedict equation is a well-established alternative that gives similar numbers.
A third option, the Katch–McArdle formula, is based on lean body mass and needs a known body-fat percentage, which can be more accurate for lean, athletic people.
To estimate the calories you actually use in a day, multiply your BMR by an activity factor that matches your typical week.
| Activity level | Description | Multiplier |
|---|---|---|
| Sedentary | Little or no exercise, desk job | × 1.2 |
| Lightly active | Light exercise 1–3 days/week | × 1.375 |
| Moderately active | Moderate exercise 3–5 days/week | × 1.55 |
| Very active | Hard exercise 6–7 days/week | × 1.725 |
| Extra active | Very hard exercise or a physical job | × 1.9 |
Once you know your BMR and TDEE, you can use those numbers as a starting point for common goals. The ranges below are widely cited general guidelines, not a personal prescription.
BMR is the calories your body burns at complete rest to keep vital functions running, such as breathing, circulation and cell repair. It is usually about 60–70% of the calories you use each day.
BMR is energy burned at rest. TDEE is your BMR multiplied by an activity factor, estimating total daily calories including movement and exercise.
This calculator uses Mifflin–St Jeor. Men: 10×kg + 6.25×cm − 5×age + 5. Women: 10×kg + 6.25×cm − 5×age − 161.
On average men carry more lean muscle and less fat than women of the same size, and muscle burns more energy at rest, so the formula uses a higher constant for men.
Equation-based BMR gives reliable baseline estimates for around 90% of people, but individual variation occurs due to thyroid hormone levels, genetics, body temperature (a fever can sharply raise BMR) and some medications. Treat it as a starting point.
Age and height are fixed, but body composition is not. Lean muscle is far more metabolically active than fat, so building and keeping muscle through strength training gradually raises the calories you burn at rest.
With age the body tends to lose lean muscle and gain fat (a process called sarcopenia). Because muscle burns more energy at rest than fat, this shifting ratio gradually lowers your resting metabolism.
The Mifflin–St Jeor equation is a widely used resting-energy formula referenced by the Academy of Nutrition and Dietetics and clinical nutrition guidelines. For general guidance on energy and nutrition see the NHS healthy weight resources and the U.S. NIDDK weight-management information. This page is for general information and is not medical advice.