What Is My Resting Metabolic Rate Calculator

Calculate your RMR to understand your basal energy needs.

Calculate Your RMR

Your Results

Select a formula and enter your details to see your RMR and TDEE.

RMR Calculation Variables

Variable	Meaning	Unit	Typical Range
Biological Sex	Biological sex assigned at birth	Male / Female	N/A
Age	Years since birth	Years	1 – 120
Weight	Body mass	kg / lbs	1 – 1000
Height	Body height	cm / in / ft'in"	1 – 300
Activity Level Factor	Multiplier for TDEE based on exercise	Unitless	1.2 – 1.9

What is Resting Metabolic Rate (RMR)?

Resting Metabolic Rate (RMR), sometimes referred to as basal metabolic rate (BMR), is the minimum number of calories your body needs to perform essential life-sustaining functions while at rest. These functions include breathing, circulating blood, maintaining body temperature, cell production, and brain activity. Essentially, it's the energy your body burns just to keep you alive if you were to do nothing all day.

Understanding your RMR is crucial for managing your weight and optimizing your fitness. It forms the baseline for your total daily energy expenditure (TDEE), which is the total number of calories you burn in a 24-hour period. By knowing your RMR, you can better estimate how many calories you need to consume to lose, maintain, or gain weight.

This Resting Metabolic Rate Calculator uses widely accepted formulas to provide an estimate. It's important to remember that RMR is an estimate, and individual metabolic rates can vary due to genetics, body composition (muscle vs. fat), hormones, and other factors.

RMR Formula and Explanation

Our calculator utilizes two popular formulas to estimate RMR. You can select which formula to use:

Mifflin-St Jeor Equation

Considered one of the most accurate formulas for estimating RMR in the general population.

For Men: RMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5

For Women: RMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

Harris-Benedict (Revised) Equation

An older but still commonly used formula.

For Men: RMR = (13.397 × weight in kg) + (4.799 × height in cm) – (5.677 × age in years) + 88.362

For Women: RMR = (9.247 × weight in kg) + (3.098 × height in cm) – (4.330 × age in years) + 447.593

To calculate your Total Daily Energy Expenditure (TDEE), your RMR is multiplied by an activity factor:

TDEE = RMR × Activity Level Factor

The activity factors represent the average calorie expenditure based on your lifestyle:

• 1.2: Sedentary (little or no exercise, desk job)
• 1.375: Lightly Active (light exercise/sports 1-3 days/week)
• 1.55: Moderately Active (moderate exercise/sports 3-5 days/week)
• 1.725: Very Active (hard exercise/sports 6-7 days/week)
• 1.9: Extra Active (very hard exercise/sports & physical job or training twice a day)

Practical Examples

Let's see how the RMR calculator works with a couple of examples:

Example 1: Sarah

Inputs:

• Biological Sex: Female
• Age: 28 years
• Weight: 62 kg
• Height: 165 cm
• Activity Level: Moderately Active (1.55)
• Formula: Mifflin-St Jeor

Calculation (Mifflin-St Jeor for Women):

RMR = (10 × 62) + (6.25 × 165) – (5 × 28) – 161

RMR = 620 + 1031.25 – 140 – 161 = 1350.25 kcal/day

TDEE = 1350.25 × 1.55 = 2092.89 kcal/day

Results: RMR ≈ 1350 kcal/day, TDEE ≈ 2093 kcal/day

Example 2: John

Inputs:

• Biological Sex: Male
• Age: 35 years
• Weight: 180 lbs (approx. 81.6 kg)
• Height: 5'11" (approx. 71 inches or 180.3 cm)
• Activity Level: Lightly Active (1.375)
• Formula: Harris-Benedict Revised

Calculation (Harris-Benedict Revised for Men):

RMR = (13.397 × 81.6) + (4.799 × 180.3) – (5.677 × 35) + 88.362

RMR = 1093.19 + 864.76 – 198.70 + 88.36 = 1847.61 kcal/day

TDEE = 1847.61 × 1.375 = 2539.84 kcal/day

Results: RMR ≈ 1848 kcal/day, TDEE ≈ 2540 kcal/day

How to Use This Resting Metabolic Rate Calculator

Using our RMR calculator is straightforward:

1. Select Biological Sex: Choose 'Male' or 'Female' as it significantly impacts the calculation.
2. Enter Age: Input your current age in years.
3. Enter Weight: Input your weight and select the appropriate unit (kg or lbs). The calculator will convert it internally if needed.
4. Enter Height: Input your height and select the unit (cm, inches, or feet/inches). If you choose 'Feet and Inches', separate fields will appear for you to enter them. The calculator will convert to centimeters internally.
5. Choose Activity Level: Select the option that best describes your typical weekly physical activity. This is used for TDEE estimation.
6. Select Formula: Choose between Mifflin-St Jeor (recommended) or Harris-Benedict Revised.
7. Click Calculate: Press the 'Calculate RMR' button.

Your estimated RMR and TDEE will be displayed. You can also see a comparison chart and detailed variable information. Use the 'Reset' button to clear the fields and start over.

Key Factors That Affect Resting Metabolic Rate

Several factors influence your RMR, and understanding them can help interpret your calculated results:

1. Body Composition: Muscle tissue burns more calories at rest than fat tissue. Individuals with higher muscle mass generally have a higher RMR.
2. Age: Metabolism tends to slow down with age, often due to a decrease in muscle mass and hormonal changes.
3. Sex: Men typically have a higher RMR than women, primarily due to generally higher muscle mass and different hormonal profiles.
4. Genetics: Your inherited genes play a role in determining your metabolic rate. Some people naturally have a faster metabolism.
5. Hormones: Thyroid hormones, in particular, significantly regulate metabolism. Imbalances (like hyperthyroidism or hypothyroidism) can drastically alter RMR.
6. Body Size and Surface Area: Larger individuals generally have higher RMRs because they have more tissue to maintain.
7. Diet and Calorie Intake: Extreme calorie restriction can cause your body to lower its RMR to conserve energy (adaptive thermogenesis).
8. Environmental Temperature: Your body expends energy to maintain its core temperature. In very cold or very hot environments, RMR can increase slightly.

Frequently Asked Questions (FAQ)

What is the difference between RMR and BMR?

RMR (Resting Metabolic Rate) and BMR (Basal Metabolic Rate) are often used interchangeably, but RMR is a slightly less strict measurement. BMR is measured under very specific, controlled conditions (lying down, awake, after fasting for 12 hours, in a thermoneutral environment), while RMR is measured under less stringent resting conditions. In practical terms, RMR is usually slightly higher than BMR and is what most calculators estimate.

Is the RMR calculation accurate?

These formulas provide an estimate. Individual RMR can vary. Factors like body composition (muscle vs. fat percentage), hormonal status, and genetics are not fully captured by these equations. For precise measurements, a clinical test like indirect calorimetry is needed.

How does muscle mass affect RMR?

Muscle is metabolically active tissue, meaning it burns more calories at rest than fat. A higher muscle mass leads to a higher RMR, even if weight and height are the same as someone with less muscle.

Can I use different units for weight and height?

Yes, this calculator supports kilograms (kg) and pounds (lbs) for weight, and centimeters (cm), inches (in), or feet and inches (ft'in") for height. The calculator automatically converts these to the metric units (kg and cm) required by the formulas.

What does a high RMR mean?

A higher RMR means your body burns more calories at rest. This can be beneficial for weight management as it contributes to a higher overall daily calorie burn (TDEE).

What does a low RMR mean?

A lower RMR indicates your body burns fewer calories at rest. Individuals with a lower RMR might find it easier to gain weight if their calorie intake exceeds their TDEE.

How can I increase my RMR?

The most effective way to increase your RMR is by increasing your muscle mass through strength training exercises. Maintaining a healthy diet and avoiding severe calorie restriction can also help prevent your RMR from slowing down.

Does activity level affect RMR?

Activity level does NOT directly change your RMR. RMR is your *resting* energy expenditure. However, your activity level is multiplied by your RMR to calculate your Total Daily Energy Expenditure (TDEE), which is the total calories you burn throughout the day, including activity.