BMR Calculator

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 and is used by most health professionals and research institutions today. 

Here’s the formula:

• Females: (10 X weight [kg]) + (6.25 X height [cm]) – (5 X age [years]) – 161

• Males: (10 X weight [kg]) + (6.25 X height [cm]) – (5 X age [years]) + 5

So, 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. To calculate your BMR, your equation should look like this:

• (10 × 72.7) + (6.25 × 167.6) – (5 × 35) – 161 = 1,438.5 calories per day

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 averages. According to the original paper that developed the Mifflin-St Jeor equation, the average male has a BMR of around 1,660 calories per day, and the average female has a BMR of around 1,400 calories per day. These numbers do not include the calories your body needs to turn food into energy and to perform physical activities.

Your BMR tells you how many calories your body burns each day at complete rest — in other words, just to keep your heart beating, lungs breathing, and cells functioning. This number is unique to your body and influenced by factors like age, sex, weight, height, and body mass.

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.

• 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.

Knowing your BMR can help you understand your body’s baseline energy needs, but it only paints part of the picture — and it definitely does not account for everything that matters when it comes to your health. 

Here’s a quick breakdown of 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 burned on top of their 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 many grams of protein, carbohydrates, or fat you should eat or whether you're getting enough vitamins, fiber, or hydration. It simply estimates your resting calorie burn, not the quality of what your body needs to function well.

• 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 impact your energy use. It’s one piece of your metabolic profile — not the full story.

Your BMR can be a helpful starting point for creating a sustainable weight loss plan. That’s because it tells you the minimum number of calories your body burns at rest. Once you know that number, you can figure out how many calories you burn in a typical day, then adjust your intake to support fat and overall weight loss.

Here’s how it works:

1. Start with your BMR. This gives you your resting calorie burn.

2. Calculate your TDEE. Multiply your BMR by an activity factor (based on how active you are each day) to estimate how many calories you burn in a full day, including exercise and movement. (But don’t worry — you don’t have to do the math yourself. You can use Ro’s handy TDEE calculator.)

3. Create a calorie deficit. To lose weight, you need to consistently burn more calories than you consume. One way you can do this is by reducing your caloric intake. In general, experts recommend a deficit of 500–750 calories per day to support a safe and steady weight loss of about 1–1.5 pounds per week (~4 pounds per month). That being said, everyone is different and working with a healthcare provider is your best bet for determining a safe and effective calorie deficit for you and your goals.

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 can help to recalculate your BMR (and, thus, TDEE) every few months if you’re actively losing weight.

And remember: Calorie counting isn’t the only strategy. You can boost your BMR and, in turn, help promote weight loss (albeit modestly) through other simple strategies, such as:

• Regularly exercising. Strength training, in particular, helps build muscle mass, which is known to raise your BMR and, in turn, help you lose weight. 

• Staying hydrated. Drinking cold water and other zero- or low-calorie beverages may temporarily increase your BMR, thereby slightly increasing your TDEE and supporting weight loss. 

BMR and resting metabolic rate (RMR) are often used interchangeably, but they’re slightly different.

• BMR is a strict measurement of how many calories your body burns at complete rest. It’s typically measured under tightly controlled lab conditions after a period of sleep and a 12-hour fast, without any recent physical activity or emotional stress. 

• RMR is a more flexible estimate of your resting energy needs that also accounts for low-effort daily activities (e.g. eating) in addition to basic bodily functions. It’s typically measured in less restrictive conditions, such as after a short fast and with minimal physical activity beforehand.