health calculator

Resting Metabolic Rate Calculator

Calculate the calories your body burns daily at complete rest using proven, science-based metabolic rate estimation models and formulas.

Formula Verified by Dr. Sarah Jenkins, PhD

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Saved Runs

Inputs

Gender

Weight (kg)kg

Height (cm)cm

Age (years)years

Body fat % (optional)%

Results

Resting Metabolic Rate

1649 kcal/day

Mifflin-St Jeor Estimate1649 kcal/day

Tip

Save this page to update your resting calorie needs as your body weight, age, or height adjustments occur.

Formula

RMR formulas

Mifflin: 10w + 6.25h - 5a + s (s = +5 for male, -161 for female). Katch-McArdle: 370 + 21.6 × LBM(kg)

Mifflin uses total weight. Katch-McArdle uses Lean Body Mass (LBM) for athletic individuals.

Step by step

How the calculation works

1Enter weight in kilograms, height in centimeters, and age in years.
2Choose your physiological gender.
3Provide body fat percentage (optional) to compute the Katch-McArdle formula, which is more accurate for individuals with higher muscle mass.

Related guides

Learn more about this calculation

Guide

RMR Calculation Guide: Mifflin and Katch-McArdle

Estimate resting metabolic rate with the exact DTC formulas, compare Mifflin-St Jeor with Katch-McArdle, and understand the limits.

Site Guide

How to Use Do The Calculation Calculators: A Practical Step-by-Step Guide

Learn the fastest reliable workflow for using Do The Calculation calculators, reading results, checking formulas, and using save, print, share, and export actions correctly.

How to understand and use this calculator

Understanding Resting Metabolic Rate (RMR)

Your Resting Metabolic Rate (RMR) is the number of calories your body burns at rest to maintain basic physiological processes (respiration, circulation, temperature control, organ function).

While BMR requires strict fasting and laboratory rest conditions, RMR is measured under less restrictive conditions, typically yielding slightly higher results (by 5-10%).

This tool estimates RMR using the Mifflin-St Jeor equation, and layers in the Katch-McArdle equation whenever you provide a body fat percentage, since a lean-mass-based formula is more accurate for muscular or leaner individuals.

The Mifflin-St Jeor and Katch-McArdle Formulas

To calculate RMR from total body weight, apply the Mifflin-St Jeor equation for men and women:

Men: RMR = 10 × Weight (kg) + 6.25 × Height (cm) - 5 × Age (years) + 5

Women: RMR = 10 × Weight (kg) + 6.25 × Height (cm) - 5 × Age (years) - 161

If you provide a body fat percentage, the calculator instead computes your Lean Body Mass (LBM) and applies the Katch-McArdle equation, which strips out fat mass since fat tissue is far less metabolically active than muscle:

LBM (kg) = Weight (kg) × (1 - (Body Fat %)/100)

RMR (Katch-McArdle) = 370 + 21.6 × LBM (kg)

These formulas demonstrate how metabolic rate scales with mass: heavier and taller individuals require more energy to sustain basic tissues, while metabolic rate naturally declines with age due to muscle mass loss.

BMR vs. RMR: The Key Differences

BMR and RMR are often used interchangeably, but they differ in measurement protocols. BMR requires the subject to be in a post-absorptive state (fasted 12 hours) and measured immediately upon waking in a clinical setting. RMR is measured at rest but does not require strict fasting or sleeping overnight at the facility, making it slightly higher due to the lingering thermic effect of food and mild physical movement.

Using RMR to Structure Daily Calorie Goals

To find your total maintenance calories, multiply your RMR by an activity factor (similar to TDEE). Never consume fewer calories than your RMR for extended periods; extreme deficits cause the body to burn muscle tissue for fuel and adaptively slow metabolic rate.

How to Use This Calculator

Enter your weight in kilograms, height in centimeters, age in years, and select your gender.

Optionally enter a body fat percentage: if provided, the calculator adds a Katch-McArdle lean-mass estimate alongside the standard Mifflin-St Jeor figure, which is generally more accurate for people who know their body composition.

Worked Example: 70 kg, 175 cm, 30-Year-Old Male

Weight 70 kg, height 175 cm, age 30, male, body fat percentage not provided.

Mifflin-St Jeor: 10 × 70 + 6.25 × 175 - 5 × 30 + 5 = 700 + 1093.75 - 150 + 5 = 1{,}648.75 kcal/day.

Since no body fat percentage was entered, the Katch-McArdle estimate is not shown — adding one (say, 15%) would instead compute LBM of 70 × 0.85 = 59.5 kg and an RMR of 370 + 21.6 × 59.5 ≈ 1{,}655 kcal/day, a close match here since 15% body fat is near this person's implied composition.

Related Calculators

Compare this resting baseline to your full daily burn with the TDEE calculator, or check your BMR estimate with the BMR calculator.

Related concepts

Mifflin-St Jeor Equation

A widely validated weight-based formula used to estimate resting energy expenditure, considered more accurate than older equations for most modern populations.

Sarcopenia

Age-related muscle loss, which is the primary cause of resting metabolic declines.

TDEE

Total Daily Energy Expenditure: the total calories burned in a day including activity.

Frequently Asked Questions

What is Resting Metabolic Rate (RMR)?+

RMR is the number of calories your body burns at rest to perform vital life-sustaining processes (breathing, heartbeats, cellular repair).

How is RMR calculated?+

The calculator uses the Mifflin-St Jeor equation, which factors in sex, age, height, and weight, plus the Katch-McArdle equation using lean body mass if you provide a body fat percentage.

How does RMR differ from BMR?+

BMR requires strict fasting and overnight rest in a laboratory. RMR is measured under less restrictive conditions and is typically 5-10% higher.

Can I increase my RMR?+

Yes. Building lean muscle mass through resistance training is the most effective way to permanently raise RMR, as muscle is more metabolically active than fat.

What is the Mifflin-St Jeor equation for men?+

RMR = 10 × Weight (kg) + 6.25 × Height (cm) - 5 × Age (years) + 5.

What is the Mifflin-St Jeor equation for women?+

RMR = 10 × Weight (kg) + 6.25 × Height (cm) - 5 × Age (years) - 161.

How does age affect my resting metabolism?+

RMR naturally declines with age, primarily because muscle mass decreases (sarcopenia). Strength training preserves muscle and metabolic rates.

Does weight loss lower my RMR?+

Yes. A smaller body requires fewer calories to maintain. Additionally, prolonged deficits can trigger metabolic adaptation, lowering RMR.

Is RMR the same as maintenance calories?+

No. RMR is what you burn at rest. To find maintenance calories (TDEE), multiply your RMR by an activity factor representing your daily movement.

Why is RMR higher in men?+

Men typically possess higher skeletal muscle mass and lower essential body fat percentages than women of similar weight, raising resting energy needs.

How to understand and use this calculator

Understanding Resting Metabolic Rate (RMR)

Your Resting Metabolic Rate (RMR) is the number of calories your body burns at rest to maintain basic physiological processes (respiration, circulation, temperature control, organ function).

While BMR requires strict fasting and laboratory rest conditions, RMR is measured under less restrictive conditions, typically yielding slightly higher results (by 5-10%).

The Mifflin-St Jeor and Katch-McArdle Formulas

To calculate RMR from total body weight, apply the Mifflin-St Jeor equation for men and women:

Men: RMR = 10 × Weight (kg) + 6.25 × Height (cm) - 5 × Age (years) + 5

Women: RMR = 10 × Weight (kg) + 6.25 × Height (cm) - 5 × Age (years) - 161

LBM (kg) = Weight (kg) × (1 - (Body Fat %)/100)

RMR (Katch-McArdle) = 370 + 21.6 × LBM (kg)

BMR vs. RMR: The Key Differences

Using RMR to Structure Daily Calorie Goals

How to Use This Calculator

Enter your weight in kilograms, height in centimeters, age in years, and select your gender.

Worked Example: 70 kg, 175 cm, 30-Year-Old Male

Weight 70 kg, height 175 cm, age 30, male, body fat percentage not provided.

Mifflin-St Jeor: 10 × 70 + 6.25 × 175 - 5 × 30 + 5 = 700 + 1093.75 - 150 + 5 = 1{,}648.75 kcal/day.

Related Calculators

Compare this resting baseline to your full daily burn with the TDEE calculator, or check your BMR estimate with the BMR calculator.

Related concepts

Mifflin-St Jeor Equation

A widely validated weight-based formula used to estimate resting energy expenditure, considered more accurate than older equations for most modern populations.

Sarcopenia

Age-related muscle loss, which is the primary cause of resting metabolic declines.

TDEE

Total Daily Energy Expenditure: the total calories burned in a day including activity.

Frequently Asked Questions

What is Resting Metabolic Rate (RMR)?+

RMR is the number of calories your body burns at rest to perform vital life-sustaining processes (breathing, heartbeats, cellular repair).

How is RMR calculated?+

The calculator uses the Mifflin-St Jeor equation, which factors in sex, age, height, and weight, plus the Katch-McArdle equation using lean body mass if you provide a body fat percentage.

How does RMR differ from BMR?+

BMR requires strict fasting and overnight rest in a laboratory. RMR is measured under less restrictive conditions and is typically 5-10% higher.

Can I increase my RMR?+

Yes. Building lean muscle mass through resistance training is the most effective way to permanently raise RMR, as muscle is more metabolically active than fat.

What is the Mifflin-St Jeor equation for men?+

RMR = 10 × Weight (kg) + 6.25 × Height (cm) - 5 × Age (years) + 5.

What is the Mifflin-St Jeor equation for women?+

RMR = 10 × Weight (kg) + 6.25 × Height (cm) - 5 × Age (years) - 161.

How does age affect my resting metabolism?+

RMR naturally declines with age, primarily because muscle mass decreases (sarcopenia). Strength training preserves muscle and metabolic rates.

Does weight loss lower my RMR?+

Yes. A smaller body requires fewer calories to maintain. Additionally, prolonged deficits can trigger metabolic adaptation, lowering RMR.

Is RMR the same as maintenance calories?+

No. RMR is what you burn at rest. To find maintenance calories (TDEE), multiply your RMR by an activity factor representing your daily movement.

Why is RMR higher in men?+

Men typically possess higher skeletal muscle mass and lower essential body fat percentages than women of similar weight, raising resting energy needs.

Resting Metabolic Rate Calculator

Inputs

Results

RMR formulas

How the calculation works

Learn more about this calculation

RMR Calculation Guide: Mifflin and Katch-McArdle

How to Use Do The Calculation Calculators: A Practical Step-by-Step Guide

Resting Metabolic Rate Calculator

Inputs

Results

Key output metrics

Metabolic rate formula comparison

How to understand and use this calculator

Understanding Resting Metabolic Rate (RMR)

The Mifflin-St Jeor and Katch-McArdle Formulas

BMR vs. RMR: The Key Differences

Using RMR to Structure Daily Calorie Goals

How to Use This Calculator

Worked Example: 70 kg, 175 cm, 30-Year-Old Male

Related Calculators

Related concepts

Frequently Asked Questions

RMR formulas

How the calculation works

Learn more about this calculation

RMR Calculation Guide: Mifflin and Katch-McArdle

How to Use Do The Calculation Calculators: A Practical Step-by-Step Guide

Key output metrics

Metabolic rate formula comparison

How to understand and use this calculator

Understanding Resting Metabolic Rate (RMR)

The Mifflin-St Jeor and Katch-McArdle Formulas

BMR vs. RMR: The Key Differences

Using RMR to Structure Daily Calorie Goals

How to Use This Calculator

Worked Example: 70 kg, 175 cm, 30-Year-Old Male

Related Calculators

Related concepts

Frequently Asked Questions