BMR Calculator
Basal metabolic rate (BMR) is the amount of energy your body needs at rest to maintain vital functions, such as breathing. It can be a useful starting point for setting weight loss or nutrition goals. Use the tool below to calculate yours.
BMR Calculator
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What is BMR?
Basal metabolic rate (BMR) is the number of calories your body burns just to stay alive — even if you remain in bed all day. It reflects the minimum amount of energy needed to power your most basic bodily functions, including breathing, circulating blood, and regulating body temperature.
Think of BMR as your body’s baseline energy requirement. It accounts for the largest portion of your total daily energy expenditure (TDEE), typically around 60–70% in sedentary adults. That means even before you factor in exercise, walking, or digesting food, your body is already burning a significant number of calories behind the scenes.
Several key factors influence your BMR:
- Body composition (fat and muscle mass): Muscle tissue requires more energy than fat tissue. The more lean muscle mass you have, the higher your BMR tends to be.
- Body size (height and weight): Larger bodies — whether due to greater height, weight, or both — require more energy to maintain basic functions.
- Age: BMR naturally declines as you get older, mainly due to a gradual loss of muscle mass and changes in hormone levels that slow metabolic activity.
- Sex: People assigned male at birth tend to have higher BMRs than those assigned female, generally because they have more muscle mass and lower body fat percentages.
- Hormones: Thyroid hormones in particular play a significant role in regulating how quickly your body uses energy. Low thyroid activity can lower BMR, while high activity can raise it.
- Genetics: Inherited traits can influence your metabolic rate, including how your body distributes muscle and fat or how efficiently it processes energy.
Understanding your BMR can be a helpful first step in tailoring a nutrition or weight management plan that fits your body’s unique energy needs. It’s also used in clinical settings to guide interventions — including helping Glo providers determine whether you may qualify for treatments like compounded semaglutide or tirzepatide.
How to calculate BMR
BMR is calculated using your age, sex, weight, and height. The most commonly used equations are the Harris-Benedict equation and the Mifflin-St Jeor equation. While both are widely accepted, the Mifflin-St Jeor equation is considered the more reliable of the two and is used by most health professionals and research institutions today.
Here’s the formula:
For females: (10 × weight [kg]) + (6.25 × height [cm]) – (5 × age [years]) – 161
For males: (10 × weight [kg]) + (6.25 × height [cm]) – (5 × age [years]) + 5
Example calculation
Let’s say you’re a 35-year-old woman who weighs 160 pounds (72.7 kg) and is 5 feet 6 inches (167.6 cm) tall. Your BMR equation would look like this:
(10 × 72.7) + (6.25 × 167.6) – (5 × 35) – 161 = 1,438.5 calories per day
This means your body burns approximately 1,438 calories per day at complete rest — before any activity or movement.
What is a normal BMR?
There’s no single “normal” BMR that applies to everyone. That’s because your basal metabolic rate is unique to your body and shaped by individual factors like age, sex, weight, height, muscle mass, and hormone levels.
That said, scientists have been able to determine general averages. According to research using the Mifflin-St Jeor equation:
These numbers do not include the calories your body needs to turn food into energy or perform physical activities. Your own BMR may be higher or lower depending on your personal factors. The calculator above gives you a personalized estimate based on your actual measurements.
What does your BMR mean?
Your BMR tells you how many calories your body burns each day at complete rest — just to keep your heart beating, lungs breathing, and cells functioning. This number is unique to your body and influenced by age, sex, weight, height, and body composition.
- A higher BMR generally means your body burns more calories at rest. This often reflects a higher proportion of lean muscle mass, a larger body size, or a younger age — all of which require more energy to keep things running.
- A lower BMR generally means your body needs fewer calories to perform basic functions. This is common with aging, muscle loss, or certain medical or hormonal conditions.
That said, it’s important to remember: a high or low BMR isn’t inherently good or bad. BMR is just one part of your overall metabolic profile, and it doesn’t directly determine how many calories you should eat, but it serves as a useful starting point for understanding your body’s energy needs.
What does your BMR not tell you?
Knowing your BMR can help you understand your body’s baseline energy needs, but it only paints part of the picture. Here’s what your BMR is not telling you:
- How many calories you actually burn in a day. Your TDEE includes more than just resting energy — it also accounts for physical activity, movement, digestion, and more. For most people, this adds hundreds (or even thousands) of additional calories on top of BMR.
- Your body composition. Two people can have the same BMR but very different amounts of fat and muscle. BMR estimates don’t distinguish between how much of your weight comes from lean mass vs. fat mass, yet that distinction plays a major role in how your metabolism functions.
- Your nutritional needs. BMR doesn’t tell you how much protein, carbohydrates, or fat you should eat, or whether you’re getting enough vitamins, fiber, or hydration. It simply estimates your resting calorie burn.
- Whether you’re gaining, losing, or maintaining weight. BMR doesn’t predict weight changes on its own. Weight change depends on your full energy balance: how many calories you take in vs. how many you burn in total.
- Your overall health status. BMR doesn’t measure metabolic health, hormonal balance, insulin sensitivity, or chronic conditions that may affect your energy use. It’s one piece of your metabolic profile, not the full story.
How to use BMR for weight loss
Your BMR can be a helpful starting point for creating a sustainable weight loss plan. Once you know how many calories your body burns at rest, you can figure out how many calories you burn in a typical day, then adjust your intake to support fat loss.
- Step 1 — Start with your BMR. Use the calculator above to get your resting calorie burn. This is your baseline.
- Step 2 — Calculate your TDEE. Multiply your BMR by the activity factor that matches your lifestyle (see table above). This gives you your full daily calorie burn, including exercise and movement.
- Step 3 — Create a calorie deficit. To lose weight, consistently burn more calories than you consume. Experts generally recommend a deficit of 500–750 calories per day to support safe, steady weight loss of about 1–1.5 lbs per week.
It’s important to note that your body adapts during weight loss. As you lose weight, your BMR may decrease slightly, meaning your calorie needs could shift over time. That’s why it helps to recalculate your BMR every few months if you’re actively losing weight.
You can also boost your BMR — and support weight loss — through:
- Strength training. Building muscle mass raises your BMR, helping you burn more calories even at rest.
- Staying hydrated. Drinking water, especially cold water, may temporarily increase your metabolic rate and support overall energy expenditure.
- Medical weight loss support. For some people, lifestyle changes alone may not be enough. GLP-1 medications like compounded semaglutide or tirzepatide can significantly support weight loss when combined with diet and exercise. Glo can help you find out if you qualify.
BMR vs. RMR
BMR and resting metabolic rate (RMR) are often used interchangeably, but they’re slightly different measurements with distinct methodologies.
For most practical purposes, including weight loss planning, the two numbers are close enough that they can be used interchangeably. The calculator above uses the Mifflin-St Jeor equation, which is the most widely validated and recommended by nutrition professionals today.
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