What Is My Basal Metabolic Rate?
This BMR calculator estimates how many calories your body may use each day at rest. BMR stands for basal metabolic rate, which is the energy your body uses for basic functions like breathing, circulation, and body temperature.
Enter your sex, age, height, and weight to get an estimated BMR calories-per-day result using the Mifflin-St Jeor equation. This is a common formula used to estimate resting calorie needs in adults.
Your result is not a diagnosis or a full nutrition plan. BMR estimates can vary based on body composition, activity, medications, thyroid status, sleep, and recent weight change.
Estimated BMR
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Frequently Asked Questions
Answers to common questions about this page and how to use what you find here.
Sources
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals
- National Academies Press: Dietary Reference Intakes for Energy
- MedlinePlus: Metabolism
- National Institute of Diabetes and Digestive and Kidney Diseases: Insulin Resistance and Prediabetes
- American Thyroid Association: Hypothyroidism
This calculator is for general education only and is not a diagnosis, treatment plan, or substitute for advice from a qualified health professional.
A BMR calculator estimates how many calories your body may burn at rest each day. It uses information such as age, sex, height, and weight to estimate basal metabolic rate. BMR does not include exercise, walking, work, digestion, or daily movement, so it is not the same as total daily calorie needs.
The Mifflin-St Jeor equation is a widely used estimate, but it is not exact for every person. Research suggests it can be more accurate than some older formulas for many adults. Still, it cannot measure muscle mass, body fat, thyroid function, medications, sleep, recent weight change, or activity level.
BMR and resting metabolic rate are similar, but they are not exactly the same. BMR is usually measured under stricter resting conditions, while resting metabolic rate may be measured with less strict testing. For everyday use, many people use both terms to describe calories burned while the body is at rest.
To estimate daily calorie needs, BMR is usually combined with an activity estimate. Your BMR covers basic body functions at rest, while total daily energy use also includes movement, exercise, work, and digestion. Activity multipliers can help, but they are still estimates and may not match your real calorie needs.
BMR can change after weight loss or weight gain because body size and lean mass affect resting calorie use. Weight loss may lower BMR, especially if lean muscle is lost. Weight gain may raise BMR because the body has more tissue to support, but the health meaning depends on many other factors.
Thyroid problems can affect real metabolic rate, but this calculator cannot detect thyroid function. Hypothyroidism may lower energy use, while hyperthyroidism may raise it. If you have symptoms such as unexplained weight change, fatigue, heat or cold intolerance, or heart racing, ask a qualified clinician about appropriate evaluation.
Metabolism and weight goals may be discussed alongside markers such as Hemoglobin A1C, glucose, insulin, triglycerides, and HDL cholesterol. These markers do not replace a BMR estimate, and BMR does not replace lab testing. Together, they may help a clinician understand blood sugar, insulin resistance, and metabolic syndrome risk.